The XD is one of the most popular guns you can get (along with the Glock). I shoot with several people on a regular basis and ALL of us think the XD is the best you can get for less than a thousand bucks. None of us has ever had a problem with the slide. You can get a dud in anything, BUT I would field strip it and lube it and try it again. Also mark your magizines and see if the problem always shows up with the same magazine. If so replace the magazine. Take a look at the XD Forum and it will give you a lot of information IMHO the difference between the Glock and the XD is in the grip. The XD sights get's on target faster than I can with a Glock.
The XD and the Glock both go bang every time you pull the trigger - they do not come with the lame excuse it must be "Broke in with several hundred rounds" before it will function right!
The reason for the slide sticking, is due to improper Re-installation of the recoil spring after one has field stripped it, as to take it apart to clean it etc....
Instead of putting the recoil spring in straight or inline with the barrell, someone has inserted the recoil spring offset, therefore causing the slide to stick.
I have had mine for quite a few years, and it has NEVER failed me or let me down one singal time.
If the xd is what you like, and it fits you, get it. Otherwise, keep looking, but I am sure you will be Very happy with it.