I use this app for studying Greek for seminary. I found some decks that others had already created and creating my own was very simple. It took a little playing around at first, but I was able to get going without consulting any help resources. I like the interface and the grading system. So far syncing across devices has worked flawlessly.
Small things keep it from getting five stars. Navigation could use some polish. Like when you edit a card, then return to the deck list and it puts you back at the top of the list rather than the section you had been viewing. If you have a deck with a lot of cards and youre making a change to many cards (like font size corrections) thats a lot of scrolling. Also, tags could use some refinement. The program doesnt store tags for use across cards. This increases the chance of typos or errors. I also havent seen much in the way of the logarithm working to increase retention, i.e. Im not getting cards Ive failed more often than cards that are easy. So overall, a great app but needing some improvements to get five stars.