I just recently jumped into the Resistance series. I was interested in the offline co-op only.
One was fantastic.
Two at first was disappointing as we couldn't co-op the story mode but the mission stages grew on us and it ended up being our favourite. Only let down was it didn't save the stats of player 2 (maybe theres a patch but I don't use my ps3 online anymore)
Three was so disappointing, we gave up after a few stages.