I'm not one to provide overly lengthy play reports unless it was really outrageous (RPGs are definitely a "ya had to be there" phenomenon, yes?) but we played two encounters--a wilderness battle and another inside a factory. The overall goal was just to get novice players some game-time under their belts, and to get to know one another (more on that in a second).
Our GM was a nice guy named Tabor who provided all the materials we needed. I brought my own rule book (since the last time I'd rolled up a PC it took forever using one book among 6 players). He'd chopped his bindings in favor of wire-bound and I took mine to Staples office supplies to do the same. It turned out to be a GREAT help and it will be a lot easier on the book in the long run as I flip through the pages at the table.
As you likely already know, the 4E D&D version of Gamma World is big on tactical combat. It's a much lighter version, but it does rely on that engine to drive encounters. But there's still a great deal of bonus/penalty dealing, and lots of rule haggling when the booster cards come in to play (especially with newbies). Don't get me wrong--the cards can be a lot of fun--but they can also end up slowing things down. Maybe it's just an effect of playing with strangers. Though playing this version made me more hungry to play Mutant Future or an older GW edition. I'm chomping at the bit to play one of those (maybe 2E GW if I had to pick).
At our game, the majority of the players was learning to play these new rules AND we don't know each other. Yes, we make believe, but it's in a very stilted manner. So we concentrate on adding and subtracting and don't actually interact with one another.
As we get more comfortable with the game, we relax and banter a bit, but no one's settled enough to be themselves. And yet, that's the beauty of RPGs right there--get people to have fun and socialize, right?
I did have fun--which is all that really matters--and I think that I'll continue to do so. I'm hoping to get in some more games. I'd signed up for a couple, hoping to try out playing with different GMs at the helm, but so far work/life has kept me from the table. When I get to play again, I hope to spend more time getting to know the players, bone-up on the rules, and really--imagining the hell out of it.