Note that there is a 3D Gallery on the market by Flikie that is not the same as this. Looks almost identical but is missing the Pinch Peek feature and for me, it wouldn't open the camera.
This app does take a long time the first time you open it as it is collecting all your images and making thumbnails and organizing the data. If you mount your SD card to your computer and move stuff around, the next time you open it, it has to rebuild again to get the updates. Well worth the wait for what it gives you.
For those asking about the Pinch Peek feature, it's useful seeing what is in a folder without opening the folder itself. Maybe not that useful most of the time, but fun to play with.
There are several other cool features in it as well...
When you're in a gallery with a lot of pictures, you can use the scroll control at the bottom to go side to side by date. There is also a toggle switch at the top to switch from grid view to folders by date. Also, if you have photos with geotags, it will show the location although this seems to be a bit funky. Another thing it does is the camera button asks me which camera app I want to open. I have the stock camera and Vignette. Once you're done taking your picture, hit the back button on the phone and it takes you back to the 3D Gallery.