It's flattering but if it's too much, it's creepy. Obviously I like it being reinforced that I look good, but I prefer it stay respectful and subtle. Overt attention makes me shy and uncomfortable.
Last saturday I was hanging out with a friend at a bar in NYC and some dude next to me just turns his head and stares right at me, makes eye contact. So I assumed he was eavesdropping or something and jokingly said something like, "See, this guy agrees with me too!" He responded in some thick Slavic accent, "Don't speak english" and continued to look at me. Awkward.