The R8 sideblades are a matter of personal taste. You can order them body colored if you like. Personally, I prefer the contrast look--silver sideblades on a black R8 are positively evil looking. I've been lucky enough to have driven the R8 (4.2L) several times on both a track and the street and I like it a lot in both environments. (Though I would definitely go manual over the automatic.)
Still, given the initial reviews of the new Porsche 911 Turbo with PDK, I think that the R8 (even in 5.2L trim) is no longer in serious contention for best super car in the sub-$150k category. If I had a spare $140,000 or so, I'd be heading down to the Porsche dealer without giving a second thought to Audi.