The reason I'm not using Phoenix full time is because of Mozilla Mail:
It just doesn't make sense for me to have both Phoenix and Mozilla in memory if Mozilla will be taking up all that memory running just Mail.
The FAQ in the 0.2 release notes say that the stand-alone mail client, now named Thunderbird (formerly Minotaur) should be released around the same time as Phoenix 0.5. Even Blake Ross notes in this mozillazine forum post he's working on Thunderbird "because Thunderbird is preventing people from using Phoenix".
Another thing I found distracting in Phoenix were all those banner ads on sites! I forgot how many sites show ads. I had blocked the majority of them a long time ago wish Mozilla. But not to worry, Image Blocking should be in 0.3.
In a related note, it's always fun watching people discuss annoying ads and popups they encounter. Poor clueless IE people.
You can still block ads in Phoenix 0.2 (and nightlies).
If you have been blocking images using mozilla, you should see a cookperm.txt file in your mozilla preference folder. That file controls the permissions for cookies, images and, for mozilla 1.2 and later nightlies, pop-up ads.
Just copy that file to the phoenix preference folder and image blocking takes effect.
For popup blocking (and a universe more, besides), try the Proxomitron.
Haven't tried Mozilla's popup blocking, really. This proggie more than good enough :)
Unfortunately, Proxomitron only works on Windows.
proxomitron works fine in wine (a little slow maybe but it always slowed things in windows too) there is a linux version based on proxomitron code I believe but the name eludes me atm.
I much prefer privoxy to proxomitron on both linux and windows. You can get it from www.privoxy.org