Yes, the second season has been OK. But being "OK" is too weak for the continuation of what I felt was the best TV history series, period.
Season 2 almost seemed lifeless compared to the pretty much flawless hypnotic complex imagery/sound/thought-scape of the second half of season 1. For example, in Sacrifice S1/Ep8 we end up with a masterful gut wrenching blend of beauty, gore, clash of religions, as if the ancient gods had risen and came back to guide or haunt ;-) the living. Yet there is plenty of human plots too with just the right mix of thought, action, nudity.
So what do we get in Season 2? A run of the mill fight for powers. Yes, there is gore, there are killings, but somehow, the magic got lost in the process. No signs of Valhalla anymore, just people wanting to kill other people. Remember the enigmatic/menacing King Horik of the first season? Every time he appeared on screen, I got a feeling he knew more of the inner workings of this world and how to manipulate people into his own plans. Can't see much of that in season 2 - the charisma is gone.
Anyway, I just kept watching - and finally, in "Blood Eagle" I got some of the magic spell handed over again. There is some beautiful cinematography of times good and bad, some new aspects of Viking life that have not been covered before and of course violence to match. The Vikings are back - not surpassing season 1, but at least rising above average and providing some much needed surprise.