I'll just sum up each of the maps quickly and you can decide for yourself.
Carnival is a good, well designed map that can favour camping, but can also make for a pretty fun match.
Trailer Park is a small, fast-paced map that's a lot of fun for pretty much any mode. It's very difficult to camp without being over-run by enemies.
Fuel is a very large map, bigger than Derail (I think) and because of that it is very boring and full of campers. It is crippled by one glitch, the ability to get inside one of the rocks. It's not even advantageous, but people just run to that every match and sit inside it for the whole game picking people off who try to get there.
Vacant is a small CQB map, but due to it pretty much all being inside, you encounter a lot of rockets, nades and shotguns. It was a good map in CoD4, but in MW2 it just doesn't work.
Strike is a pretty average urban map. Decent for most game modes, nothing special about it, but a solid map.
All in all, I think it's worth it. It's definitely better than the Stimulus Package.