Everything improved! Well, pretty much everything. The rules are better written, better organized, etc. Hacking and Close Combat are expanded. There are a fair number of new units and skills. And a few other bits added on. However, the core of the game remains. You should have no trouble making the transition, just read the
N3 rules carefully to see what has changed. It is a very well written ruleset.
That said, a few of the old issues still persist. But this time,
CB has someone answering questions and maintaining a
FAQ. Plus there is the wiki.
Jump back in. The change from 2nd ed to 3rd ed is, this time, an improvement