I bought a GH-625XT in Spring 2013 to replace a GH615B which had done me sterling service since 2007 (albeit having to be replaced under warranty within a year). In general, the GH-625XT was an improvement, particularly in terms of sensitivity and accuracy, although there were some bizarre and pointless little changes in the software which severely affected the usability of the watch for real-world running use. I mentioned this in the thread http://usglobalsat.com/forum/index.php?topic=4661.msg14328#msg14328
from early in my ownership of the watch. At that point I hoped the problems would be addressed by some firmware update (as things usually were with the GH615), and have been dismayed to find that this is not the case.
To reiterate, the specific, maddening, pointless change I am referring to is the behaviour of the OK button when on a run. With the GH615, if you pressed this button, it would pause the watch, and if you pressed it again it would immediately resume the watch, which is exactly how it should be. With the GH-625XT, though, when you press the button, it puts it into a kind of display mode for 10 seconds or so, which you have to dismiss with another press of the button if you want to resume the watch. This is completely unnecessary - for one thing, no-one needs the display for more than a couple of seconds, and for another, any button presses shouldn't be 'intercepted' by this screen but should go to the underlying function instead (i.e., should resume/pause the watch). Because of this, I have screwed up the time recording of so many runs in the dark. To make matters worse, the little alert sounds have been changed so you can't even do it by ear. On the old watch, when you pressed the button to pause, the watch would make a little descending series of notes, and when resuming, an ascending series of notes. This new one does not do this, so you basically have to stop and turn on the light to make sure you've stopped or started the watch correctly, which is clearly unworkable for a serious runner.
Still, I've lived with this for 20 months. But now I've bought a Garmin Forerunner 220 to replace the watch, because of hardware failure which has rendered it unusable. The OK button has fallen off and disappeared somewhere, which is exactly what happened to the 615M in the end (although after much longer than 20 months). On top of this, the cover for the connector at the back has broken off, and now the connection itself is dodgy - I have to push the connector sideways slightly to get it to connect properly and hold it like that while transferring data. Less than 2 years is not a good lifespan for a GPS watch like this, I would say.
It's a shame, as I really have no great desire to go over to the Garmin camp. I think you potentially have a great piece of kit here, but it has some serious flaws. You need to address the silly software issue (the GH615, or GH625 as upgraded via firmware, was fine in this respect). You also need to make the buttons and connectors more robust. I hope to come back to GlobalSat at some point in the future when you have a new watch which addresses these issues.