Yeah, I felt the same way about Dench too. I actually really like Judi Dench, but I wished M was played by another actor/actress since it was a reboot. Still doesn't bother me as much as this, since Casino Royale and QS are in a different continuity from the previous Bond films, it is easy enough to shake off. The new ST on the other hand, is kind of claiming to be both, by going to the end of the current continuity and using a time travel plot to return to the very beginning of continuity and starting over.

It reminds me of them feeling the need to pass the ST film torch from Kirk to Picard by having them share the same movie. Sure, it wove the TOS crew films tighter together with the TNG crew films in an odd sort of way, but it really wasn't needed, and was one of the weaker bits of the storyline. Reminded me of those silly debates I used to have with other kids when I was younger, "Picard could out smart Kirk any day of the week!" "Oh yeah! Well Kirk could kick Picards butt before he even had a chance to start thinking"