I have been using Photoshop.com for a while now and this app is much much more stable. It's also about 10x faster, I'm impressed.
It's just like Adobe to build a bloated application.
I have a copy of CS3 installed locally but I often just want to do a quick edit and was using the online PS version (I've tried aviary too) and I wasn't very happy with the other options.
If you want to compare try uploading a file in both apps. In photoshop.com it takes about 30 seconds for even the dialog box to open.
What I don't get is why hasn't Adobe done this already w/ Photoshop? A online version that is subscription based. The industry is slowly moving towards that direction, maybe they will follow.