Yesterday, we went to see Shrek 4 - "Shrek - Forever After" at the cinema. Not the 3D version, because that's just a silly overpriced gimmick which means you have to keep your head vertical...
Shrek 1 was a work of genius in the way it reworked fairy stories and went against the grain. Shrek 2 was a pretty good continuation of it, that heavily referenced and parodied modern culture. Shrek 3 was so easily forgettable I can't find anyone who can remember it well, though I've found several people who think they've probably seen it.
Shrek 4 doesn't parody anything really. It just uses most of the same characters, with one new major character (the evil Rumplestiltskin), who is largely as in fairy tales rather than being a clever twist on it. It's a fun film, and a decent one - probably better than 3, but nowhere near either 1 or 2 in standard. There are a couple of really clever moments, and one really romantic one, but they're the exception rather than the rule.
It's like they tried writing a decent-ish story with the same characters (albeit in a parallel universe where Shrek was never born), and it's just all a bit too pedestrian in comparison with the first two - as if the clever writers had run out of steam. Fun, but not fantastic.