I love this app. I use it extensively both on my research, as on my free time. I also miss the lack of support of .xls and .ppt, but I can work around it by including pdf versions of the files I need.

Moreover, it has a great support from their dev team.

Bottom line: 4.5/5. Why not 5? Because I’m sure this application will improve. It’s too soon to give it 5. :)