I have not seen the newest version of Gamma World yet, but I think perhaps one of the finest versions of the game was Jonathan Tweet's Omega World [Polyhedron #153 (Sep 2002)]. Jonathan Tweet "got" what Gamma World was all about: 50's B-Movie science, over-the-top action and characters, and the fact that scientific realism is pretty much optional.
Part of the problem is Gamma World has always been schizophrenic about what it includes in the game. Every version of the game tries (mostly unsuccessfully) to marry far futuristic gear (e.g. robots, death rays, etc.) with whatever the current technology of the year the version was produced (e.g. tape reels in the 70's- early 80's versions, now nanotech). Each version quickly becomes dated as real-life science moves on and careens off in directions no one suspected it would.
In the Omega World version, I think Tweet did a great job of stripping the game down to its most essential pieces, all the while avoiding most of the problems of other editions. That being said, if you are looking for a complete game, I would second the vote for the 4th edition. It has a funky and wonderful vibe all its own.
