Tiny Scanner does a good job of automatically detecting the edges on documents. Unfortunately it doesn't do a great job at a whole lot else. The resolution isn't the sharpest, and the options you have for editing a scan aren't the most intuitive.
I'm also unhappy with the lack of export options Tiny Scanner makes available: all you can do without a subscription is email the scans or open them in another program. That's not too convenient if you want to get them on the cloud.