4.5.4 or Beta?

I’m about to redownload Unity, but I’m wondering whether it’s worth it (and safe) to go with the current beta, or if I should use 4.5.4 instead.

I’ll be developing a serious and important project, and would hate to lose progress or backwards editing compatibility by using the beta if it’s unstable, but I would like to make use of the new UI features.

Pros, Cons? Any help is appreciated.

The 4.6beta is the 4.5 code with the addition of Unity GUI. Unless you need the Unity GUI code, download the official 4.5 version.