Oracle release the production version of XE on Feb 24 and I should be trying to upgrade to it this week.
As for the beta 3 here is my mini-review:
With Oracle Database XE, you can now develop and deploy applications with a powerful, proven, industry-leading infrastructure, and then upgrade when necessary without costly and complex migrations.
Oracle Database XE can be installed on any size host machine with any number of CPUs, but this free version of the world's leading database will store up to 4GB of user data, use up to 1GB of memory, and use one CPU on the host machine.
The installer is pretty straightforward and easy to setup. The only weird thing I experienced was that I was unable to connect to other databases I had setup on my 10g Client install. Since XE replaces the system paths, everything looks at this new Oracle Home. So I basically had to move all my entries on my tnsnames.ora to the one in the XE directory. Simple and logical.
Apart from that little glitch, the database purrs!! I was connected to it through Toad, Coldfusion, DB Solo, and Aqua Data Studio with no problems. The database web tool is extremely intuiative and easy to use.
This database is a great starter database if you haven't messed in the Oracle World. Every feature is there as far as I can see, except well the 4gb of data limitation.
Here is a great blog by Tug, who has created a viewlet that shows you how easy it is to install this wonderful database.