I watched them all. They are indeed "not the same." Which is exactly what makes them objectively inferior to seasons 1-3. The ensemble cast is the strongest thing this series had going for it, and season 4 did not involve the whole cast. Each episode was someone's little side story with perhaps 1, or rarely 2 other characters, filling in all the rest simply with old flashbacks to make you think they had the whole cast working on each episode. A well played out story (and it was pretty cleverly done, and very intricate) wasn't nearly enough to make S4 live up to what this show so easily managed with the entire cast involved.
Somewhere, I came across the info/rumor/whatever that far and away the biggest reason they couldn't get the whole cast together to shoot episodes was because Michael Cera is the world's largest pussy douchebag. Or some such.