You must have gotten the 2-7x32 scope, not a bad peice of glass. That's what my old CFX came with, and what it's wearing now, but it belongs to my little brother now. I went to bigger glasss, mostly to stretch my shooting time. A 44mm vs. 32mm is a lot brighter, longer.
The spring buzz/twang will ease up some as it breaks in, but to make it go away will require a tear down and tune. Worth doing, but most guys like to shoot them a bit first.
I think all the Gamo boxes have a Shadow on them, the CFX may be their flagship model, but I think the Shadow was the biggest seller.
The rotary breech is a nice system once you get used to it,but be careful. If the pellet doesn't make it all the way into the barrel, you can squish or shave the pellet skirt. At best, it screws up accuracy, at worst, it can damage the breech seal.
Don' like the muzzle brake either, and no, it's not really a brake, just cosmetic and a place to put the catch for the cocking lever. I never thought the cocking effort was as heavy as they say, either.
Don't know if you realize it, but the synthetic stock is hollow. Adding some weight to the butt can make a big difference in the way the rifle feels. I put a pound of Duct Seal in mine, it really improves the balance.
These really are excellent guns for the price, I just got one of the .22's. Don't know what you're using for pellets, but mine liked Superdomes, JSB Exacts, and JSB Match Diablolos. Later.
Dave