Don't know about people's experience level with them but my other carry gun had one on it. Worked well. My duty holster was a little tight to snap, use a Level III Safariland but had no problems with the slide stop and it's functioning.
I have sense retired my Colt and sold it. I carry a Kimber now and will be adding one, once I have some other projects taken care of. I also must rotate my grip in order to release the slide. This pistol is also my SRT pistol. In this business, when you have to reload, then you got to do it fast because if you're having to reload in a deployement, then things have gotten pretty ugly and you must get your firearm back in service.
My buddy, who is the primary medic on our team, was playing with his Colt that he built up himself. It has an extended release on it. We went to the range Monday and shot a BUNCH of rounds. He had no problems with it.
I guess it just works for some and others it don't. But I have seen it work for me and will be getting one soon.
Hope this helps, good luck.