It does feel a lot tidier, and looks more modern than it did in 2.5. My only cricism is that the final page could do with re-ordering. I'd forgotten to chown the directory I created for testing, so configuration.php wasn't writeable. I almost missed the warning, though, as it appeared towards the bottom of the screen. Not the end of the world, you'd just have to go back through the installation (or create the configuration manually) but would certainly be annoying.
I chose not to install sample data, so proceeded straight to the back-end (what's the point in reviewing an empty front-end?). Through versions 1.0, 1.5 and 2.5 the back-end has remained largely unchanged. Joomla! 3.0, however, brings a huge interface change. The basic navigation is unchanged, but the addition of a submenu on the left gives easy access to related functions and settings. The tiled icons present in older versions are gone from the Control panel, leading to a much, much cleaner feel. Those shortcuts haven't been lost however, but have simply moved to the 'Quick Icons' menu on the right hand side of the page.
One addition that will follow you around the back-end is the implementation of a useful 'Help' menu. Providing links to the built in help files, as well as useful resources (the JED, Translations etc), I suspect it's something that will be well used. It does, however, get disabled at times you may need it. As a rule of thumb, if the rest of the menus (components, extensions etc) are disabled, then the Help menu will be too. As it's links take you to another page (as opposed to a lightbox containing information pertinent to the current page) its not really a major issue. I would like to see the option to add page specific help at some time in the future though (although it does mean more work for extension developers!)
I'll not detail every screen, as some of the changes really are limited to the interface, but will highlight those that I felt really stood out.
The global configuration seemed like a good place to start. The actual functions remain the same, but the interace now uses bootstrap tabs in place of the basic text links that were present in previous versions. The submenu on the left, however, provides a quick way to jump to configuration for a specific component. This is now the home for component configuration (though the Options button in a component will still open the configuration, it just takes you here).
For me, one of the most important changes is here - browse to the Users Manager configuration. Although it's defaulted to "Yes" you can now set "Send Password" to "No" to prevent Joomla! from emailing their passwords in plaintext when they first register. I'd have like to see this defaulted to the more secure setting, but at least Administrators now have the ability to close this horrific oversight in security without needing to resort to workarounds.
User Management appears to be largely unchanged, with one exception: You can now add notes relating to users. When a note is available against a specific user, an option to display the note will appear under their name in the Users list.
Whilst obviously not of use to everyone, it's a feature that may well prove invaluable to those who do have a need for it. Whether that be as a means of recording (for example) why a subscription has been extended, or simply so that you can record in more detail who they are (businesses, for example, may wish to record which office a user is in.)
I've a feeling that a substantial proportion of the world probably uses K2 by now, but that doesn't make the inbuilt article editor any less important. The changes here are ones that you'll see on almost every other content related screen in the back-end: the panes on the right are gone and are now bootstrap tabs at the top of the page.
Although all the familiar functions are there, there's something about this screen that feels quite unfamiliar. I've not had any problems using it, so I suspect the change in interface has been just about dramatic enough to make my brain think "Do I know what I'm doing?"
The media manager on the other hand feels very familar, though the interface has definitely been tidied somewhat. I no longer get the vague feeling of mess that I did with older versions.
Additional options are available for Images and Links, though in truth I've not played around with these nearly enough to decide whether or not I like them.
As with the rest of the back-end, everything feels a lot cleaner and tidier, though I still can't quite decide whether I prefer this screen over it's Joomla! 2.5 counterpart.
Now here's a screen that has improved vastly. The module assignment screen was always a tad messy with the Menu Assignment box at the bottom, and potentially limitless panes on the right. Now, though, everything is in Bootstrap tabs. There's a nice wide area on the right hand side of the screen for the Module Description (great for those modules that feel the need to write essays!) and the basic options occupy the left hand side.
I installed a module that I know uses a lot of panes, and sure enough things looked a lot better without that additional clutter on the right hand side.
Having created a very basic article, I moved to the front-end to see what changes I could expect there. The default template (Hathor) is quite minimalistic, but also very functional. I won't delve too much into the front-end's look and feel given that most people will be installing their own templates anyway!
One thing I did want to check-out, though, was mobile support. So I viewed my basic article on a Samsung Galaxy S2. Rather than having to scroll horizontally (as has been the case in the past), the site fit itself to my screen. Of course that's quite easy to do with text, so I edited my article to include a rather large image (1200px wide in fact). In the past responsive templates have either handled it well, or completely failed to address the issues at all. Straight off the bat, though Joomla 3 resized the image to fit my screen, and when I turned my phone landscape (without refreshing), the content resized. To put it simply, it works exactly on my phone as I would expect it should!
The cynic in me did think it might break if I manually set a width when editing, but even then the site corrects so that it displays properly on my phone.
Modules positioned on the right move below the content, which may be an issue if you've used a module to display information relevant to the content (such as extra information about a topic) but generally seems like a good move. The end result is that I'll be able to read content on Joomla! 3.0 sites without needing to tinker with zoom levels to try and achieve the balance between text-size and minimal horizontal scrolling. Never a bad thing in my books!
Older versions of Joomla! did have the ability to edit content from the front-end, but it wasn't often used as the editor was incredibly basic. Joomla! 3.0 improves on this somewhat, providing options relating to Editing (obviously), Publishing, Language and MetaData it's now far easier to control your content without needing to log into the back-end.
Somewhere in there, presumably, is the ability to add new content from scratch, but I must confess I can't find it!
The influence of Twitter Bootstrap is clear on every aspect of the site, though I think that's a real benefit as it gives a good consistent UI throughout. For the experienced Joomla! user, back-end navigation hasn't really changed, but new routes you can use to be more efficient have been added. The look and feel of the new back-end template (Isis) is a huge improvement over previous versions, which were definitely beginning to look very dated.
Front-end functionality is always going to rely largely on what the administrator does with their site, but the built in compatability for mobile browsers is a definite benefit in a world where everyone seems to be reading on the smallest possible screens!
The official advice is that most users should probably stick with Joomla! 2.5 until the next Long Term Support (version 3.5) is released next year. I suspect, though, that many people are going to see the improvements in Joomla 3.0 and start using it as soon as they can. There's certainly no harm in trying it out, and hopefully we'll be seeing a lot of sites based on Joomla! 3.0 in the near future. It's a very polished product, and now it's really down to the extension and template developers to build upon it, but they've definitely been given a good headstart
The official stable version is set to be released tomorrow, so I strongly recommend you head over to Joomla.org to download a copy so that you can have a tinker! Really, though, I'd probably try and hold off from upgrading sites on 2.5 for the time being - I did run a successful update from 2.5.1 on an unused demo site, but as it contained little more than the default template and components I wouldn't call it an exhaustive test!