I came across JustPictures! the other day.
Best gallery app I have used.
I tried F-Stop and QuickPic as well. Both are very nice...and fast.
But what I like about JustPictures!, is it's not only fast (like the others) but you can also display Picasa Galleries as well...and not just your own.
I didn't see that option in F-Stop or QuickPic.
I have dozens of galleries in Picasa, so it's nice to have quick access to them within the gallery app with the rest of my local photos.
There are other Picasa apps, but they have all seemed slow and/or clunky. This one is by far the best I have tried.
The only thing about it that some of you may not like is that it only displays pictures, no video. Which is fine. I like the app so much, if I want to watch any video I have taken, I just open up the gallery app for that.