It works. What kind of decoders do you plan to program? For plain DCC decoders there should be no problem. For loading sounds into a Digitrax sound decoder there shouldn't be a problem. For other sound decoders the supplied 14v DC power supply *may* be a bit anemic. People on the Digitrax Yahoo group report needing up to a 18v DC supply to successfully program Soundtraxx and some BLI/Paragon decoders.
If you use Windows 64-bit be very careful about how you install the drivers. There are countless posts in the Digitrax group about people having problems with the PR3 drivers in Windows 64-bit and most are due to not following the directions and having the wrong drivers installed. Find the right instructions at
http://www.digitrax.com/tsd/product/PR3XTRA/32-bit Windows seems to not have this problem.
If you're a Mac person then it installs without a problem.
Using Decoder Pro and JMRI with this works well. Again, depending on the decoders. Currently JMRI/DecoderPro is having a difficult time handling some of the special CV's for most ESU LokSound decoders and TCS's new WOW sound decoders and I think even Zimo's decoders. Most of these use an extended CV range above CV255 and they all use different methods for accessing them. but work is being done to fix this and hopefully before too long they will be fixed.