Best PDF reader. For me biggest feature is not locking file while reading. I can't image developing some PDF with Jasper with any other PDF reader. 10 years ago people looked at me as some god when I show them how to test jasper rendering PDF with JUnit and SumatraPDF and not deployng whole app to Websphere and clicking through it. Decresed time to see changes from 4-5 minutes to 2-3 seconds.