Yes, they're designed to give you pleasure. The Cyber one is unreal like and so is the blue alien like thing as well. But, good feelings are available from many of the sleeves!
I have my
STU unused, waiting for ride. It's "too bad" I love my hands so much. Problem is partially with maintenance and sound. I'd be happy to use my
FleshLights more often, but washing and drying them off, I don't have a good private spot for that. Thin walls as well, so a
FleshLight or basically any artificial happy hole makes a lot more sound than my hand and lubricant.
All in all, with good lubricant and decent maintenance they can be a lot of fun! For the moment I think I actually have ... wait, four sleeves? Yeah. And as mentioned, I haven't used the
STU one yet. Got to go for it some day soon. I'm a lazy wanker!