I got the stock as a birthday present, and it's great. When all the other reviews say that it's difficult to install they're not joking, it really is. I had no problem getting the top pin in but i had to tap the bottom one in with a hammer. This results in absolutely no wobble at all. The only problem with how tight it is is you may find yourself reluctant to dissassemble your marker, it's a pain to get off.
Whether or not you can see down the sights depends on what mask you have. I have a VForce Vantage. I can still use the sights, but you it takes a bit longer to acquire a target than it normally would. I would reccomend a red dot sight. I won't take this off the mark of the stock though, as with many you can't see the sights at all.
It's completely made out of plastic, but it's incredibly solid. The flip plate in my opinion isn't really too useful, but it looks cool.
All around great stock. If you like the looks, go for it. 9 because it's a pain to get on and off.