My main bike is a 2008 Specialized Tarmac (carbon). Have had zero issues with it. Not sure how many miles but I'd guess 25-30k. I also have a couple Specialized Allez and a Tricross - all aluminum. No problems with them either.
I also have an early 90s Tommasini Super Prestige which is steel. I feel like that one flexes a little too much when I ride it. I didn't really buy it to ride though. It's slightly too small for me. I bought it as a display piece as I think it's one of the most beautiful bikes I've ever seen.