Generally speaking I'm not bothered at all by being "checked out." On days when I feel like I look pretty frumpy and I get that kind of attention, it's a huge ego booster. On days when I make the effort to be dressed up and look extra cute/sexy, then again it's an positive affirmation of one's sexiness which is always good.
But of course that doesn't mean that men should go around staring at whoever they choose. There's a huge difference between making your interest and appreciation known and being full out creepy. Plus some women are more comfortable than others being "checked out," and her body language will pretty much tell you where she stands on that one. So in short, I like it as long as it's done tastefully, but not everyone will, so use discretion.