I missed a lot of stuff from the book in Season 1, and S2 was clearly too late to bring all of that back. I loved S1 and still enjoyed S2, but I think it would have been even better if they'd made S1 longer. There was much more that could have been told there.
S2 was definitely more like Dr Who than the apocalyptic stakes of S1, but I guess you can do that only once.