This is the smallest of the four maps, and probably one of the smaller maps in the entire game. The area is very similar to "Nuketown," with two main areas divided by an open play area. Unfortunately, "Drive-In" is one of the two main offenders when it comes to sniper nests. One sits near each spawn point, so there's usually a tussle around those two areas early in matches.
However, unlike "Hazard," it is hard for snipers to really dominate the matches. There are a number of interior hallways running along the sides of the map and enough debris between the two spots that smart players will be able to navigate to the sniper spots without too much trouble. I've noticed a tendency for matches to drift more towards the interior sections, which is more fun, though I suspect the reason has more to do with the blind corners. Still, with a well-oiled team, the map is enjoyable.
"Drive-In" is the smaller of the four maps and "Hangar 18" is the weaker. Oddly enough, I ended up enjoying it a little more than the other groups - though, I also grew to like "Stockpile," which features a similar setup. This is a fast map with lots of interior hallways. Most battles gravitate towards the main hanger (which features a SR-71 Blackbird as a centerpiece), though you'll have to keep moving. Even then, the forced sniper areas (they're in every map, unfortunately), crush some of the tactical areas.
Of the four maps, "Hangar 18" is one of the more entertaining to explore. The map is based after Area 51, so have fun taking in the sights (just watch out for the sniper's sights).
I absolutely hate "Hazard," though based on the last few games I played through, this is becoming one of the more popular ones with the player base. If you're a casual Call of Duty player who is on the fence about Annihilation, I'm tempted to suggest passing on the pack just because of this map.
"Hazard" is a rework of "Cliffside" from World at War, but as I mentioned earlier, it takes place on a golf course. The layout is nice; there are hilly areas and a couple of tight areas for fights along the perimeter of the map. This really could be one of the best maps in the game, but every match I played turned into a sniping shooting gallery. If you can't get to a nest early, or don't come with a good scope, you'll die a lot and, quite possible, quit in frustration.
Next to "Hangar 18," this is my favorite map in the bunch. I love maps that encourage tactical play with groups, and that is exactly what "Silo" offers. The setup offers something for nearly every play style, and so far I haven't found one dominant setup on the map. There are a few sniper spots, though sitting and waiting isn't a strong tactic. There's also room for long-range players as well as areas for faster, close-quarters battles. The map is well designed and really makes players think about what they're doing rather than allowing for one tactic.