I have several Betsey Johnson bags, and I love them, although I usually use higher end designer bags like Chloe, Gucci or Marc Jacobs.
What I like about the Betsey Johnson bags are the punk style. I also like the hugeness (they are great for schlepping things around).
The quality is not the same as my $1500 bags, but I don't expect it to be. I consider them on par with Coach or Dooney in price point and quality, but MUCH edgier.