Slow and clunky. Every affect has to be applied. If you want to undo anything prepare for a long walk back.
It's a lot more fun and fast to work with CameraBag 2 with its dynamic building blocks and instant effects.
On the plus side, the tilt/shift effect is cool and unique. The u-handle possibilities open some creative doors as well, but the whole process is so slow and painful and produces such mediocre results (relatively speaking) that I can't imagine trying to do serious work in Snapseed, whereas with CameraBag 2, one could quickly process an entire pro set with individual tweaks per image.
Snapseed is a very slow toy.