The download and installation process was a breeze and in no time I was up and running with only one little glitch - the themes page in the admin interface reported an error due to the lack of
GLOB_BRACE support in the glob() function on non-GNU systems - I dev, test and host on OpenSolaris. I resolved this by changing the screenshot line in system/classes/themes.php as per the last comment in Habari bug #182 (it was the quickest and simplest solution).
With that out of the way, I was ready to get reading and playing.
Well, I'm impressed. Habari seems to be very well coded (thanks to the use of OO and good coding practices) and seems to be low on resource hogging too. The directory structure has been well thought out so upgrading shouldn't be much of a problem.
There are two limitations that I can immediately see that are stopping me from switching whole heartedly (for the moment): the lack of sub-pages and WP 2.5 import functionality. I don't think these will be a major issue to resolve: I don't think it'll be long before the WP 2.3.1 import plugin (provided with Habari) is updated to support WP 2.5 and it seems easy enough to add the sub-page functionality via a plugin, so I may just do that and create my first Habari plugin that adds sub-page functionality (I've got to learn the ins and outs of the plugin system first ;-) ).
I'm sure I'll encounter other limitations as I progress, but for the moment, I'm quite impressed (this may be slightly influenced by the never ending "500 Internal Server" errors I keep getting from Wordpress at the moment (cos it's a memory hog)).