I have 2 G2's in olive drab and black and have carried them off and on for about a year now and they still look practically new. I've carried the black one the most and aside from some small scuff marks on the bezel, you'd think it was just purchased. The good think about the G2 Nitrolon is that it doesn't show wear as much as aluminum does and it doesn't feel cold to the touch during winter. It's the least expensive of all Surefire lights, but by no means cheap in quality. It's a fantastic light if you're on a tight budget.
Naturally, the aluminum ones are more expensive, but most are available in type III hard anodize finish, have lockout tailcaps, Lexan lenses and are pretty much indestructible. I prefer aluminum Surefires, but it all depends on what you're looking for in a flashlight. Is it going to be your EDC or just a backup light? If it's going to spend most of it's time in your glove compartment or toolbox, then the G2 would make a good buy. If you want a Surefire light to carry everyday and use often, perhaps an E1e or E2e with a KL1 LED module would fit the bill.