Recently rewatched all seasons, still think it's a great show. First few episodes of S1 have the overdone CGI blood, it gets turned down a bit after that and doesn't detract from the show then. Don't really mind the Spartacus actor change but agree on Naevia being worse off for it. Doesn't help that the S2/S3 Naevia is a very different character from S1/PQ. She was clever and careful in S1, dumb and cruel in S2/3. Changes her in to an unlikeable character which makes her romance seem awkward. Still, a great show.
Also recently noticed that the actor that plays Glaber was in LOTR as one of the elves (the one that says "The dwarf breathes so loudly we could have shot him in the dark")