I often srick to just a few defining features. I try to go beyond just hair and eyecolour but I'm also not a fan of whole paragraphs of description. I usually go for a couple of sentences if it is a relatively minor character and maybe a bit more if the character is more important.
Excessive anything is bad, of course - the number of fight/battle scenes I have skimmed through because someone's fallen in love with their historical/military research (or, I sometimes suspect, too many fight scenes in blockbuster movies) and goes on for paragraphs and paragraphs and pages...
