Nothing wrong with him IMO, apart from the fact he actually liked Kerry Packer (who WAS a dickhead) for some reason.
Andrew Hansen (from the Chaser's War on Everything) summed him (Packer) up quite well.
As for Tony Greig, what he has said and done over the years hasn't
exactly attracted me to him, to put it that way (i.e - sounding so comical in the commentary box as to transcend the very notion of contempt).
As a batsman, he was obviously much better than Flintoff, for reasons already mentioned.
As a bowler, he was (as pointed out) versatile, bowling both fast-mediums and offspin (although his offspin was cannon fodder to David Hookes, a notable underachiever who was apparently a pretty poor player of spin bowling, so I don't know how significant this is). I can't say whether he was superior to Flintoff, although the stats suggest that Flintoff was.
It is impossible to compare them as ODI players, obviously (Greig, ironically, barely played them, despite his pioneering role in the development of the ODI game, in question).
I'd probably take Greig, based on the strength of his batting (and almost certainly his captaincy, too).