Trixbox CE is definately one of the best (if not the best) packaged open source asterisk solution out available. We currently migrated our 1.2 asterisk solution over to the 1.4.18 build (latest on Trixbox) and it has been great so far. Definately one of the best things about Trixbox CE is being able to use HudLite (which is a client plug in) but also having a much better web user interface on the server. Features such as the FOP, Endpoint Manager, CDR Reporting and the ARI to login and view the interface really make a big difference if you are used to just working with asterisk with no user interface.
Kudos also go to the community and Trixbox for making the Package Update Manager for allowing great updates via the web interface. FreePBX is also the other inteface packaged with the system. Over all, a very welcome addition to our infrastructure vs. the older asterisk build which we had in 2 years ago.
I am also very happy with the fact that you have access to the Mysql Database and customization of the PHP scripts so you can make quite a few optimized changes on the server to make Trixbox display data how you want.
However, be warned, to really get the most out of Trixbox CE, you still need to have quite a good expertise with Telephony, Linux but most of all, you need to understand the asterisk architecture still because there are still somethings you need to do that the user interface can't handle. (Probably only 10% but the 10% are critical features.) Paging, Call Groups, Trunking are all done much better in this newer release!
Normally after an install, I assume you would go to the IP Address of the machine, instead I get the Apache screen asking me to contact the administration. Rather than typing the IP Address of your machine, after install, you need to go to http://cp.trixbox.com/ . You can only hope that cp.trixbox never goes down or you are hooped because this is how you have access to the machine. Why it was designed like this I could understand for managability, but it places way too much reliance on Trixbox to run your phone system. If this is the case, i recommend you purchase support for the system because you are depending on them, but I dont' recommend running the free Trixbox Pro version and relying on Trixbox.
The big difference with Trixbox CE and Trixbox Pro is that Pro is more of a managed service where as CE is more of a standalone.
You can find out more about Trixbox at http://www.trixbox.com/
My preference is definately the CE version since there is so much functionality and flexibility, plus you don't depend on the connection to Fonality to view the user interface.Popular OS choices
Trixbox and some of our other vendors all seem to prefer Cent OS for asterisk, I am not sure why but that seems to be the general consensus, although from the looks on the Digium site they seem to prefer Fedora Core.