Well, yeah. Solo Alpha Site is the only map you have a chance. But FF was a coop mode. I had tons of fun even with random European strangers through achievement websites--delegating roles (designated Splaser dude to nail Wraiths as they got dropped off in the preserve), letting people know the positions of enemies, etc. There really weren't any *bad* maps, although there were definitely ones with more fun enemy routes and options for how to defend.
I think part of the issue is that the enemies in Reach FF aren't aggressive enough--you can hold out solo on a whole mess of the maps, and they aren't built with the same sorts of chokes and zones. Corvette and Installation 04 are the only maps that really work for me, the rest are just middling, and then you have things like the Nightfall one which are just a pain.