Pretty good. Has some issues. With long documents occasionally just loads a blank screen (even if I leave it to load for ages) and if I turn my phone sideways it often jumps back to the start of the document and loses my place. Otherwise it is good  loads fast and so far works on all of my documents I've asked it to open. Easy to read  good zoom levels  and works in all orientations of the phone.
March 27 2015