Well, I've watched the first few episodes of Smallville: Season 6 on Blu-Ray and I'm entirely underwhelmed. And that's being polite. I've purchased Heroes: Season 1 on regular DVD and I'm currently watching Transformers on regular DVD and both offer, IMHO, better upscaled video quality than what I've seen from the Blu-Ray Smallville set.
It's pathetic that Warner Bros. couldn't produce a better transfer. There's a better review here:
Maybe they're seeing some shots I'm not, but a 4/5 "Video" ranking is, to my eyes, way too aggressive. The Blu-Ray version of the sixth season of Smallville is fathoms away from "reference" material and is, at best, low Tier 3 material from a PQ perspective. That's fine if one wants a picture that's better than broadcast TV, but not at all good for those who were expecting to see a great deal of "pop" or a lot of clarity. The colors are spot-on accurate, which is about the best thing I can say about the PQ.
Color me disappointed.