KRK's are very popular. However, to me they've always been more on the "consumer side" or even "DJ side" of the line than the "professional studio" side, with all of their equpiment (no offense intended to consumers, DJ's, etc).
KRK is very affordable and they aren't bad at all, just not what I would buy if I were buying for a studio.
for home use and for personal use, yeah, if the price is right. but for me, there are alternatives.
I've had the ATH-M40s and while they're OK, I don't plan on buying another pair.
The Sennheiser HD-280's are great lower end cans for studio and they are VERY comfortable.