I got 'em. I really really like them. I love the sensation of Blackout, because I know what to do and where the jumps are and everything, but my eyes don't trust what my hands are telling me to do. The look of it is so different even though it's a pretty true to the original remake.
Ghosttown is awesome. It really is unlike any map in Halo, to me. Had some good fun with objective customs there last night.
Avalanche is just chaotic fun too. I heart big team games, so I am predisposed for loving this type of map. But it's just explosions everywhere with 12+ people on the map. Wish I could get 16 in there, but the lobbies are set up for 12 and I didn't have enough for a custom 16.
I thought they were great - likely my favorite expansion set of the Halo 2/Halo 3 packs, though I did like the Sanctuary/Terminal/Relic ones for H2.