I think they're great. As people who've fought Samuel Peter or Bob Sapp can tell, hitting a huge motherfucker is quite the workout. More resistance pushing back or something. And it teaches you to stop hitting like a bitch. I grew up with a 60 lb. everlast that SUCKED in my room and used to hit it all the time w/o gloves or wraps so I learned that lesson early on.
Never hurt my hand either, except once when I punched a steel reinforced wall out of anger like a 13-year-old in a Blink 182 video. Boy was that stupid. The funny thing is the right hand was fine, it was the left hook I followed up with that fucked my hand up. I burst a tendon in my middle knuckle...LMFAO.
Let that be a lesson: stay away from crazy women and their crazy, overbearing mothers who blame you for all of their problems. And I've heard all the arguments from people to use wraps, big gloves, blah blah. Irony has hurt me really badly every time I went against pro advice like that EXCEPT FOR THIS INSTANT. I've never hurt my hand training. Ever. And its because I learned to punch like a MAN, DAMMIT.