I got into UDK after watching Zak’s video tutorial series, and everything made so much sense that i was able to see the possibilities right away even though i had no modding & game development experience. Kismet was one of the biggest factors that attracted my attention since i’m not a programmer. So my suggestion is, make them watch the tutorials and let them decide for themselves. If they can’t see the simplicity and functionality themselves then i doubt that they’ll have success with any other engine.
On documentation, we will have more in the future, just give Epic some time. 