This thing is amazing!
Even though the room my home studio is in is pretty dry (heavy curtains, solid amount of carpet, and a pretty chunky sitting area acting as a bass trap :)), this reflexion filter helps even more in getting clean vocal tracks at home... I couldn't believe it - all the things everyone's saying when talking about this one are true.
Mounting this on a mic stand proved to be slightly tricky, but I managed to figure it out. Unfortunately, it does add a lot of instability to the stand, it becomes very top-heavy and it's easy to knock it over... sand bags are not really a good solution, a tough mic stand is probably the best you could do. I'm using this with K&M 260/1, so perhaps the circular base that it has is not a good choice, and a tripod-like mic stand would have been a better one, don't know. For the time being, sand bags will have to do.
Regarding any cons... I don't have much to say here. This is a grrrrreat product if you cannot afford to have a vocal booth in your home studio.