what VC games have you downloaded and why?
also what are the must VC games to get?
http://www.vc-reviews.com/
Lots of good reviews there. My personal faves that haven't been mentioned are:
Sin & Punishment, Ristar, Sim City, Bomberman '93, Bonk's Revenge, Landstalker: The Treasures of King Nole, The Story of Thor, F-Zero X, Paper Mario, Lylat Wars and Gunstar Heroes.
If you only get 3 games:
Bomberman 93 (awesome for multiplayer)
Paper Mario (Excellent value for money)
Sin & Punishment (Best shooter EVER!)