Uses more air(not a problem w/ 20oz. tank)
Weird to get used to
This was relatively easy to install. I got mine from Bass Pro Shop for $60. I put it in that night and it didn't work. So I messed around with it for a few days and got it to work . I found that I had the wrong spring in(it comes with a new one and it and the stock one got mixed up). The thing is fast. @ least 15BPS. The only thing is that it uses more air. Thats not a big problem if you have a 20oz.
If you want full auto w/out paying for the E-Grip, go for this.