I kinda see Fedora as a great office desktop and a good development platform. We use it on our servers (hosting servers) but it is heavily cusomised with security enhancements and packages.
I think the reason why the php4 - 5 upgrade was delayed was due to the fact that many PHP4 scripts originally didn't work in PHP5 (we still use PHP4 on our web servers), now many projects have made their scripts compatible the PHP5 upgrade makes sense. The late MySQL upgrade however I have no idea, on our SQL servers it was the first thing I rebuilt with previous Fedoras.
Maybe they did spend too much time patching everything to make it work with GCC4 and too little time with new features. Its a pity 5 is going to be delayed so long as I have been looking forward to that since I heard some of the included features.
In hindsight I'd say that Fedora 4 does seem more of a intrum release, getting the technology ready to work for 5.
I think I need to let my wife to be (on Saturday) try it to gauge a proper ease of use