I wouldn't say it's painful. Roger Mason Jr. was painful. It's frustrating watching him miss so many open teammates, but he's not booting the ball off his foot, and he is able to hit shots. I simply don't expect him to be consistenly able to do that against playoff teams where quality of shot becomes much more important.
I really like Neal, and I think he's playing great. I know I've said that, but I wanted to continue to make that clear. He's done as much as anyone could reasonably expect in that fill-in role. It is, however, just a fill-in role. If the Spurs can't get Carter, I'll settle for the starting point guard for the third best team in the western conference as my backup.