The problem with him is that he is a 650 point model with movement 3.
You make a big deal about low movement values but I only see that as an actual problem when you're playing an objective game (of which I don't play many). All Dwarfs have a movement value of 3 anyway, which is a weakness of the army rather than Thorgrim himself, and in any case they are still only an inch slower than most other armies' infantry when moving and charging and only two inches when marching. It would be more of an issue if Thorgrim didn't have a Ward Save, as he could then be taken down pretty easily by Empire and other Dwarf armies that use cannons (although it would be impossible to one-shot him on the first turn as he has 7 wounds), but he has a 4+ Ward normally which becomes 2+ against attacks with multiple wounds, killing blow or heroic killing blow. Sure, many characters of a similar points level have a steed to swan around on, but according to the cannon rule that hits both a hero and a monster, other characters on monsters will thus find it difficult to engage a Dwarf army anyway. The best Dwarf tactics don't involve running around like headless chickens and more often rely on using ranged weapons to force your enemy into traps fortified with some very defensively powerful infantry, and Thorgrim is very defensively powerful.
The thing that worries me more is Thorgrim's offensive power for his points value - he does wound everything not in magic armour on 2+ and everything in magic armour on 3+ and also boosts the Ancestral Grudge table to make it more likely that all Dwarfs have hatred, but his attacks are only Strength 4 (Strength 5 on the charge thanks to Resolute), which means that he will only be able to inflict a -2 armour save penalty at best, and even that will only last for the first turn. Nevertheless, Thorgrim looks like a great unit for holding up a big horde of chaff and stopping it from engaging Hammerers or Ironbreakers that could be used for stopping stronger units, as he will have his 2+ armour save and 4+ ward to rely upon to keep him alive and a -1 or -2 penalty is all that's really required for killing chaff, so he has his uses. Certainly if you're looking for a more aggressive character, Ungrim is your Dwarf, even when he's not Incarnate of Fire, and is a lot cheaper both moneywise and pointswise than Thorgrim. If GW release him as part of Warhammer Legends, I'm definitely looking to get him (not only would he look great with my Fyreslayers but he would be a lot cheaper, and most likely metal). However, Thorgrim would look great lined up with the rest of my Dwarfs, and would be fun to play with as I don't play competitively.
It all depends on whether I am able to go to a Games Workshop this week to be able to order him. If so, then I may get him while I can, if not, then it's not too much of a big deal as I have a lot of stuff for my Dwarfs anyway, and all is not lost.
