He's certainly the most charming trashcan on wheels I've ever seen.

As maligned as the prequels are, I must say, I remember hearing loud cheers of joy in the theater when R2 went all hardcore on a couple of Federation droids, dousing 'em in an oily substance and setting them ablaze by turning his little jets on them. I was almost waiting to see him do a little jig to "Stuck in the Middle with You" and carve off one of their ears. So yeah, even in a cruddy Star Wars movie, R2 pretty much rocks the party.

R2D2 has soul, man. That's what makes him great character. He's a robot with very human traits: courage, fear, mischief, joy, sadness, loyalty. And he expresses all of them non-verbally and with zero facial expressions".

a toy (action figure?) designer made a series of Star Wars characters as if they were a part of a kurosawa movie that was never filmed. Here's r2d2:
http://www.sillof.com/images/Customs/samurai%20wars/c-sam-ryuuto.jpg

He (and Chewie) are more important than you ever imagined: http://www.hxbro.com/A_New_Sith.html