That's pretty cool.
I been looking at the 24, 28 and 35.. and ofocurse the 40mm pancake ( i owned it for a whole day before i returned it and got the 50mm f/1.4) but i still feel that i need a wider focal length, the 28 f/1.8 USM completes the trinity.. but it is so expensive (overpriced if you ask me) so i'm trying to find subsitutes, the 35 and 28 are very old and doesent have the USM, plus, they are noisy and somewhat slow compared to the 40mm pancake.
What i really want is the 28, but since i don't have the money (maybe somewhere summer 2013) and want less mm.. the cheapest, most silent, best looking, newest.. is the pancake.