I guess I just didn't buy Moriarty's character on the show for some reason. Part of it is that I felt that character was overdone and the acting - like so many crazy bad guys - felt more like caricature than anything remotely real. And the fact that Sherlock just happened to be foiling many of Moriarty's ventures rang a little false as well. I don't know, something about his character and the way they worked him into the show just didn't work for me.
And yeah, I actually didn't even recognize Cumberbatch in Tinker Tailor. He's obviously a versatile actor though. Here's hoping we see more of him in the future.
EDIT: I think if you consider the way Sherlock's eccentricities are manifested in the show and in the movie, along with the music in both, and along with the moment's where he's making deductions and the camera zips around showing all the elements he's noticing, it's a little difficult NOT to see similarities that feel too close to be coincidental. That's not a criticism of one or the other, it's just noting that some elements ARE very close.