Elevation wins my vote for worst map I've played in a really long time. Like, early Foundry days long time. It's pretty much a jetpack only map, and the design is so poorly thought out I'm absolutely amazed that the Bungie testers thought that this map has actual competitive merit. Nothing but bridges and hallways, which is the death knell of any strafing that one might consider doing. The z-fighting is absolutely atrocious, there are random capture plates and flag stands that show up in a Slayer game, random ramps that dead end, and you can pretty much camp behind the teleporter frames and assassinate anyone stupid enough to use them. My favorite part of the map has to be the area that you spawn in on the bottom level and have only one way to higher ground; a lift that shoots you high enough to become an instant target for everyone on the other team, no matter where they are. I could go on, but I really don't want to sound like a total asshole.
I still haven't played all the maps yet (and I had to quit a game because everyone on my team bailed out right away), but if this isn't the worst of the bunch then I'm about to be really let down.