You can actually do far worse with some of the chain restaurants than McDonald's.
For example, burgers at Ruby Tuesday's run from 800-1382 calories. McDonald's Big Macs are 540 calories, "only" 250 calories for a regular McD's burger.
Other massive calorie dishes at Ruby Tuesday's:
Chicken & Broccoli Pasta - 1013
Italian Shrimp Pasta - 1246
Parmesan Chicken Pasta - 1302
Strawberries & Ice Cream - 914 cals
Signature House Salad - 438 cals (WITHOUT dressing!). You're better off eating McDonald's hamburgers @ 250 cals a piece.
I'm only using Ruby Tuesday #'s because it's what I have available, but rest assured that just about every chain restaurant out there's like this. Want healthy? Eat at a local restaurant or cook it yourself.
So is McDonald's healthy? Not really. BUT there are many healthy-appearing options which are actually far worse for you.
As with everything in life, moderation is key.