They're not bad off road, they are not fun on icy hills, unless sliding backwards is fun, well maybe then they are fun on icy hills actually.
They seemed to have gotten noisier after about 20K miles of driving, I have uneven tread wear as Im running too narrow of a wheel (fjcruiser 17's), and mine actually have cracking along the sidewall between the sidewall tread lugs, but that may be due to the narrow rims.
In the mud they actually do pretty good, but like other mud tires they are still prone to the really greasy stuff, as maybe there isnt enough void between the lugs to work like paddles (agricultural or cut boggers). Though in some conditions, chains on grapplers could make swampers have to work hard to keep on top. If you bounce down alot of rocky river beds though, chains arent really an option.
On the road the grapplers are alright, but mine howl as loud as the cummins and make a long drive longer. Seriously, at 65mph people beside start looking around expecting a turbo prop plane to be taking off beside them.
But, they work as well or better than most of the other mud radials used on DD's, they arent the top on marks list, but as a radial for a DD in comparison to the other brands they arent a bad choice IMO, and they look really great. They actually get a lot of positive feedback wherever I go with them, not that, thats why I bought them, but it is nice to hear.