The power of sparrow isn't the UI, it's the deep integration with gmail. More specifically, the labels are the killer feature.
I use fewer site-specific browsers than I otherwise would because of memory usage, but these days many of us have 4-8 GB RAM and running one or two SSBs doesn't break the bank, so to speak.
A. They don't automatically close. (I think you can change this for each web app individually, but I would like a browser-wise setting). This wouldn't be a big issue, if not for...
B. The close button is freaking tiny. I can dismiss Growl notifications by clicking anywhere on them, which is much nicer on a laptop than trying to move to a small button.
C. The notifcation windows resemble what Apple calls panels. [1] The problem is, "Panels float above other windows and provide tools or controls that users can work with while documents are open." [2] The user isn't meant to be closing panels often, which is why the title bar can be small. Chrome's notifications feel out of place in that regard.
1. http://maxcdn.googletutor.netdna-cdn.com/wp-content/uploads/...
2. http://developer.apple.com/library/mac/#documentation/UserEx...
That's strange. They automatically close for me and I didn't change any settings anywhere.
I would be nice if they were just Growl notifications however.
Sparrow's ui is mostly fine - but a bit frustrating at times. I find occasionally I miss new messages - something that never happened in mail.app.
But, it really does combine the best of both worlds between Gmail and a desktop app.