While admittedly the Sentry Gun was a bit weak before they buffed it up, and while it IS quite easy to take out, it seems slightly ridiculous how much they shoot people through walls even if the slightest bit of you pops out of a corner. Plus for people saying how a perk rendered them useless before... uh yeah that's just about every killstreak so why should the sentry be different.
I dont get shot through walls but they mean business if you take a peek around the corner. There used to be a delay when you peeked out. Im fine with the way they are now.
Wait, sentry gun is overpowered?
In my opinion, that and the Guardian are ridiculously easy to get rid of. If you don't run engineer, look at the minimap, listen for the noise, look at the kill feed or remember where it killed you from, I guess they can be tricky to handle.