The strong humour makes up for the ultra-thin premise.
Hugh Grant (George) and Sandra Bullock (Lucy) are excellent together, they share solid chemistry. I like Grant's performance the most, bringing a likeable but flawed vibe to his character. Bullock is good in her role, too.
It probably is a forgettable film, but I do enjoy the humour. It keeps things pacing well, at least until the third act where the plot kinda ends with a whimper. Nothing else standouts, especially the supporting cast.
They could've/should've shaved twenty minutes or so off the run time to keep it fresher, but all in all I'd deem 'Two Weeks Notice' as one that's worth viewing.