My sister cuts her own hair these days. It always looks amazing, except for the back...
She does little pixie cuts on herself, with custom angling in the front (she likes weirder styles). I don't think it would work for just anyone, because she has pretty great hair (though she doesn't agree). It pretty much does what she wants....no fly-aways or frizzyness, so the imperfections of her home haircut don't readily present themselves.
I just did a home-trim, because
a) it's too expensive to get a cut, even if it's at a $12 place
B) the stylist ALWAYS cuts off way more than I ask him/her to
c) my hair's long enough that I can just trim the ends, even in the back, by pulling them up in front of my face.
If your hair is short, like my sis's, I'd go for it...but be prepared to go to the stylist for a repair job!!! It's sort of worth the risk, right?