ExtremeTech.com

Picnik isn’t about trying to be an online Photoshop, but rather is intended as a way to give digital shutterbugs a convenient way to fix up their snapshots. Its competition in the installed software world is Picasa rather than Photoshop. But don’t think it’s a simple rotate and red-eye correcting app: Picnik offers plenty of impressive capabilities.

LifeHacker.com:

There’s quite a bit to Picnik, actually: you can do the basic resizes and tweaks that most other free image editors we’ve talked about here at Lifehacker can manage; however, Picnik also comes with some nifty special effects, and can be used with a whole plethora of community photo sharing sites, i.e., Flickr, Imageshack, Photobucket, etc. It’s not as powerful as Photoshop, naturally, but for a browser-based image editor, Picnik does a fine job.

Infodoodads.com:

My significant other just walked by and asked “Is that Photoshop? ” A reasonable question, as Splashup both appears and works in Photoshop style.

AppAppeal.com:

Splashup (formerly Fauxto) is used to both modify and create images on the fly. With a similar setup to Photoshop or Gimp, Splashup provides an interface that makes it quick and simple to modify any image from your computer or the web. In addition to simply uploading images, Splashup allows free-transformation of the image, layer effects, multiple brushes and much more. With the ability to share and download images when complete, it could replace a desktop image editing program very quickly.

Downloadsquad.com: one of the best online image editors we’ve seen so far

This web-based image editor has all your usual features like resizing, cropping, and some basic effects like sharpening, blurring, and pixelizing. But there are also some pretty advanced color controls and you an even use layered effects. 
Splashup runs in Flash, so you should be able to use it with any web browser on any operating system. Unfortunately we were unable to get it to load an image properly using our new Eee PC (pictured above). That’s a shame, because when you’ve got a portable web-enabled Linux computer with only 4GB of flash memory, that last thing you want to do is bog it down by installing applications. For now we’ll just have to keep using Picnik and Snipshot to do our image editing on the go.