I loved Watershed after I got over the initial new-album-new-guitarist hate that everyone had. It's really a quality album, though I did have some issues with the song structures and lack of the signature haunting Opeth instrumentals. I think Fredrik is a great addition, but I sure hope that Axenrot matured on this next album. He's a great drummer, absolutely amazing... but Lopez was from another planet.
Another complaint I had with it was that the songs constantly stayed in some sort of middle ground; none of the songs were terribly aggressive, and none of them were immaculately serene. I'm loving the 70's prog influence, but I don't want it to cloud what I already liked about Opeth. And thumbs up to Per, because I was iffy about him in the band during GR, but he really proved himself on Watershed.
Also... I didn't like Watershed's gimmicky endings/fade-outs. The songs that ended with people talking/laughing/etc. simply seemed like lazy song writing. Very anti-climactic and unsatisfying.