I haven't seen Shrek 3 yet. Is it not funny?No, it is not. My children wanted to see it in the theatre, so I paid good money. It was pretty stale, I thought. The kids were getting fidgety by the middle, and they sat still for (ugh) TMNT*. We all really like the first one, though.
I would wait until it no longer qualifies as a New Rental, and then go for it. That way you minimize your loss.
*Teenage Mutant Ninja Turtles Thank-you for reminding me. I need to go grab my winter/festive sigs.