I recently got a 360 to replace my Harmony 680. I tried to migrate my Harmony 680 configuration to the 360. The way you do this is you run a connectivity check, which tells the web site what model you have, then you do an update. The last time I did this, migrating from a 688 to a 680, it worked perfectly. This time, it seemed to import the configuration, but it did not control my TV correctly. My TV uses a scheme in which one command brings up the input menu, another scrolls through it, and a third command confirms the selection. The 360 seemed to be failing to issue the confirm command when switching activities that used different inputs. I tried tweaking the delays, but that didn't work. I don't think the problem is with importing my old configuration, because I ran into the same problem when I created a new configuration from scratch. I ultimately found a workaround, but I think the 360 has some bugs.
The other thing that I noticed is that not all of the custom commands seem to be configurable. There seem to be a few hardcoded custom commands for each activity that cannot be removed.
Despite these issues, I generally like the 360. It has a nice complement of buttons (a few more than the 520, although it is otherwise similar), nicely laid out, and I like the fact that the buttons vary in shape and texture, which makes them easier to identify in the dark. I also like the display and green backlighting.