Princess Tutu is ostensibly a shoujo magical girl series, from its name all the way down to its romantic quadrangle, and it fulfils the expectations of that genre wonderfully. But there's also an element of artistry that elevates it beyond simply being a well-done genre work. It's not just that the series wraps itself in high culture like ballet or literature -- it's that it actually manages to comment intelligently on these things while creating a beautiful visual work.
Princess Tutu filters the usual magical girl narrative through the strange logic of fairy tales and a healthy coating of Utena-esque surrealism. As the series progresses, the story begins to fall apart in an intentional and revealing way, and things get increasingly metafictional. What results will be a delight to both anime fans looking for entertainment as well as postmodern aficionados like myself.
There are a lot of relatively stand-alone episodes, and these tend to drag. I won't deny that the middle section of Princess Tutu bored me most of the time. But the end pulled it all back together, and it might have one of the best conclusions of any anime series I've watched. Don't be fooled by the silly title -- this show deserves to be taken seriously.