Hubby had to tell me that Hugh Laurie was a Brit. **blushes** I had no clue who he was prior to House.
In truth, the accent isn't what bothers me, and neither are O'Mara's acting abilities. It's his looks. He looks nothing like a hot Italian. He doesn't even look like a hot Irishman. He looks like a pretty ordinary guy really, and that's fine for a lot of roles--even other romantic leads. It's the complete antithesis of Morelli though. It's not just that he doesn't look like **my** picture of Morelli; it's that he doesn't look like the kind of guy that every woman in Trenton wants to bed.
Being able to play the bad boy isn't enough in this role, neither is comedic timing.
To me, though, "hot" isn't all about looks. An "ordinary" looking guy (or even a not-so-great looking guy) can move WAY up on the "hot" list if he has that intensity. And (to me) when you see Jason O'Mara act, that intensity is there and kicks up the looks. I said he was creepy on "The Closer" - he was sexy-creepy. He was good-looking, but then when he started talking he was intensely...creepy. And yet, still hot.
Then again, "hot" is in the eye of the beholder. There will be people who'll love him (lots of people on the EW site were thrilled with his casting) and people who won't - just like the rest of the cast. They'd never be able to please everyone - I don't envy casting agents when they're casting that type of movie that comes with books with a big fan base for beloved characters.