I have been a fan of Amanda's since All That, and she is still funny. Too me, it's as simple as that. If you like the Bynes, you will like this film. It's harmless fun and quite funny in parts. Vi's wacky Sebastian accent and mannerisms are entirely unrealistic but made me laugh so hard at some points I almost choked on my popcorn.
And anything that gets teens reading Shakespeare (maybe) is a good thing for me.
On a shallow note, Tatum Channing is quite *ahem* freaking hot. He also does a good job with some of the film's tougher scenes.
Some of the side characters are VERY broad, but they are broad in "Twelfth Night" so it's cool.