I give it a solid sideways. Wasn't their best season, wasn't the worst. Had some good stories, however I noticed the slo-mo photography got overused this season which I thought took away from the effectiveness of the show. Used to be it was only used to show Clark's super abilities, but this season they seemed to use it for everyone and in an extended time drags. I've seen that style in movies and was not impressed there, so that took a little away from the show for me.
For the finale - I thought it was pretty good. I know I read of some fans not liking it because he didn't fly enough or wear "the suit" enough. I recalled the writers said they never intended Clark to ever wear the suit or fly in the series, so the fact they did both at the very end I think was a major concession to the fans to allow the transition from the show to all the adult movies/shows out there.
I was a bit disappointed with how they threw Lex in at the end. If they have more of a lead up - like what Lionel was planning - dropped in the episodes leading up to it, maybe it wouldn't have been such an "out of left field" part. Also didn't care for the memory wiping piece at the end - other than allowing Lex to forget Superman's true identity, doesn't explain how he becomes his arch enemy in the future, unless the implication was it was simply in his nature...
But those were all nit picks of my personal take - overall I thought it was a solid ending to the series that did justice to it. Since the series ran so long there would be no way writers would have been able to accommodate every fan's favorite things in the episode, so I think they managed to cover the important pieces.
Was a fun show to follow over the years. Wonder what the CW will pair against Supernatural next season now.