I've played around with it a little bit at home, but have not used it in a production environment. I've also read quite a bit of feedback from other users who have migrated already.
Probaby the two biggest complaints I've heard has been dealing with the new plotting software & the re-vamped icons. I've yet to mess around with the plotting, but I can go along with the new icon colors being a little confusing at first.
The new customer defaults layout is really nice...no more editing of metric.def or english.def files.
Probably one of the largest modeling enhancements I've seen so far is the support for the wireframe creation of True Type fonts. Basically, you choose a font, & font characteristics (size, bold, etc.) and UG creates the curves for you & allows for placement of the curves in a planar manner. The curves aren't associative, so that's the only let down there. I believe this new function is supposed to mature into 3D modeled text that is recognized as some sort of feature.
Associative curves look interesting at a glance. Something different that will make UG even more flexible than it already is.
I don't know what too early would mean to you....are you asking in terms of the number of bugs in NX3 or what? What are you migrating from?
I realize this isn't an overwhelming amount of info, but if you want an overview, check out UGS' website in the GTAC support area & take a look at the What's New guides.
Tim Flater
Senior Designer
Enkei America, Inc.