Being totally familiar with IPB v2.3 (front and back ends) I find it necessary to start a list here. Administrators may be aware of some of these issues, but no list exists so I'll start one. Btw, I already expressed my appreciation in KFDM's thread...
First off, an excellent CSS Guide to help you set font and background colors: IP.Board v2.2 CSS Guide. The version is 2.2 but works for 2.3.
Settings are disabled (or not visible) in the personal profile for a member to adjust Notification Options, Moderation Options, and Settings. Font color inside the info boxes down the left side of a profile needs to be changed so it is visible (currently to dark).
Smilies are not showing in the post screen box. "Show All" produces a list on white background and the images do not show. And please, add a few of the more common, popular ones.
Board Message when there are no new posts appears on a very light background with very light text.