If you are a fan of the series and want to see the movie nonetheless:
1. Wait for DVD. Rent, don't buy.
2. If you absolutely must watch it at the theater, watch it in 2D. The 3D on this one made my eyes bother me all through the movie and hours after.
Sorry, that's the only advice I have to make it more bearable. Now I'm going to go find the entire series and watch it so maybe I can flush the memory of the movie out of my head.