A lot of fun, it not hit and miss.
We use the SCGT system (guys I play with like point). On the first game I was able to make a first turn charge (4D6 move + 2D6 charge) straight into Manfred (aka Big Fred). He munched half of his wounds. Battle went on for another turn but eventually Big Fred won. Whilst only a couple of pools between them, Big Fred is way more powerful.
On the second game I used him definitely. Deployed behind a house as he was staring through the window at some cheese (possibly brie, probably halloumi). He then worked as a counter-charge unit. During this skirmish he ate a wounded Big Fred, got confused and chewed on a building (mystical), finished off that Hex flying wagon thingy, used ghost calvary as toothpicks and then bared down upon a cowering necromancer.
In the third game everyone teamed-up on him so his damage output was greatly reduced before he did anything (only a 5+ save and no regeneration).