Other than the obvious size and brawling issues and less than stellar defensive reflexes and schooling he was marvellous in most other ways. Few heavyweights can compete with him as a counter puncher and combo hitter. I think his punch gets underrated a bit, he definitely hit hard enough to seriously hurt all but the most iron chinned heavies. Superb conditioning and durability. I agree he was was very well-rounded but I think he was a bit better and more comfortable at matadoring fighters at ring centre than tracking down movers or other counter punchers. I think fast pressure with infighting ability would run him hard too. I'd imagine him having a tough time with someone like Frazier for that reason. He was versatile and adaptable but could still be troubled by styles at the extreme ends of the spectrum rather than having a specific vulnerability. Great fighter.
Took too many punches, plus he wasn't exactly the right size for the emerging super heavyweights of that era. Holyfield is #4 on my list of ATGs more for his nearly unmatched champion's heart as much for his four title wins. Had he come around in Louis, Lewis, Larry and Ali's peak periods he would have even given them a great fight (though I don't think he'd win).