I've used pixlr advanced editor to do manips and photo shop is much more powerful. It's good if you're just doing a edit of a photo or slapping text on a picture, but not if you want to do a full on manipulation beyond combing two images or digital painting. I primarily recommend it for people who want to edit their photos and don't have the budget for photoshop elements or paint shop pro.
It's not pressure sensitive when I used my stylus with it, which sucked. And it's not compatible with abr files like gimp, so you can't load new brushes that you find on DeviantART which is a big problem for me. Also it is not compatible with actions for photoediting. Aaaaand you have to have internet to use it. Since it's not a download, it's hard to use without internet. I can use my copy of gimp or Photoshop elements without having internet if I'm on the bus or train or somewhere that's a dead spot or I don't trust the wifi or can't access it.