The Bottom Line: Run away. Although it installed reasonably well, it would quickly become a problem.
This is highly intermittent. Sometimes a reset, per the manual, will completely reset the DIR-615A1. Other times it resets the IP address but not the password. Over the last four months I have spent hours with this thing. It was in use as a second AP, and its lack of performance was not critical.
It did not work reliably when new. I discovered a Firmware Update and installed it. It seemed to be better for a while. Within a couple weeks, no one could connect to it.
I removed it and attempted to reset and reconfigure it. This happened numerous times. I would get it out, plug in a cable and try the reset. This should only take a few minutes. It always took an hour + to get it working again. To save a changed setting, you press the Save button. It may immediately respond, or it may wait 15 seconds, or it may simply refresh the page without saving. It was very entertaining. I recently decided that I am wasting my time.
It is waiting to go to the next Electronic Recycling Day.
The bottom gets very hot. Perhaps because the little rubber feet are so short, the vent holes on the bottom are blocked. The heat could be the source of the intermittency, and short life that so many people have encountered.