Cons Isn't for top games. No cooling fan but there is a power port for running a fan. Where you'd put it I don't know, I'm not up on these things.
Summary First off this add on upgraded my (pretty meager) system to a Windows Experience Index of 4.3 for the Graphics score and 5.4 for Gaming Graphics, and after you run the included overclocking software you get a Windows Experience Index of 4.3 for the Graphics score and 5.4 for Gaming Graphics (same numbers). I think that telling you those scores probably tells you more than anything else I could type here. I haven't tried any further overclocking, I don't game.
I can now watch video without much lag (my processor still plays a roll in that) and if I had a better system I wouldn't have any lag at all. I did play a few free games online and they seem more 3d than before, but that may be just me trying to see too much into this new addition.
I've had it for about a week and haven't had any instability issues at all. i.e. works as you'd expect.