Spent all night playing as Medic/Support last night, rolled with my maxed UAV and healing gun, barely got any kills but it was still surprisingly fun. Maneuvering between the other 3 teammates, dodging friendly fire AND enemies attacks made the game feels like a lite bullet hell game.
Hope Arrowhead will get a bigger budget for a bigger sequel next time. The procedural generated maps work well enough for a while until every map feels a bit samey and things get slightly repetitive. Would love to see a separate campaign in future sequels, some of the set pieces / stages in Dead Nation are awesome, hope to see the same in Helldivers. Perhaps we can have a separate Campaign mode, and what we have in Helldivers now can be a Conquer (or Managed Liberation) mode which offers unlimited replayability and longevity as long as the online community stays alive.
If you can get a few friends to play with you, I would definitely give it a go, it's a blast to play in co-op.