They do improve your hearing when turned on, yes.
I've tried several different versions and have yet to find any I really didn't like. They all seem to work fine.
I had a set from Radians that I used for several years. The only thing I didn't like was the fairly random Auto-Off "feature".
I've also used some from Pro Ears. They also work fine but are expensive. I didn't see any benefit from the extra cost, but to each his own.
I now have a pair of Caldwell's. They were like $29 at Dick's. They also work just fine.
If you're rifle shooting, you'll want a "slim line" version. Unfortunately, Slim Line versions also offer less protection. I use and recommend a set of foam plugs under the muffs if you're shooting especially loud guns, which means virtually any handgun and high-powered, high-velocity or short-barreled rifles. Even with foam plugs on under them, you can hear better with the muffs than without them.
The technology of the electronic muffs has come a long way in just a few years. It's almost hard to go wrong.