I think people's problems with Cruise stem mainly from his personal life. Judging him strictly as an actor, I've always found him to be quite capable, professional, and dedicated. I admire the care and hard work he puts into his craft, whatever issues I may have with other aspects of his life that are really none of my business anyway.
That said, I just don't think he's the right choice for Napoleon Solo. Particularly since he's already the lead of another spy-revival franchise. It gives the impression that the movie might not be distinct enough in its character and flavor. Now, Ritchie directing is encouraging; the Holmes-Watson relationship in his Holmes movies feels reasonably similar to the Solo-Kuryakin dynamic, a resourceful, larger-than-life comic hero bantering with his more serious sidekick. So he seems like a good choice. I'm just not sure Cruise could pull it off. Then again, Cruise has done comedy in the past, and he did a rather chameleonic turn in Tropic Thunder
. So maybe he could play a different enough persona to make it work -- but I'm afraid the studio would be pushing for just more of the same stuff he does in M:I.