Still, there are many different free PDF readers available and many are choosing not to use Adobe. Firstly, Adobe Reader XI can be painfully slow at times and with the awesome amount of ability it packs into one program, I suppose it isn't too abnormal that it might at times slow down. Adobe PDF documents are universally used in business, education and personal exchanges and the documents themselves can contain very rich graphics and diagrams.Īdobe Reader XI is the standard in PDF document viewing, yet it does lack in several areas. If you want full compatibility with all versions of PDF documents, then the only original PDF viewer is from the source and that is Adobe.