In my only game with the 8th edition book I fielded it. So far I'm still on the fence with it, with being on the side of liking it more now. I used it to tie up a skeleton horde which it did with no problem. It did some serious damage on the turn it charged in as I had generated five steam points and so did some nice damage. However, I did roll a misfire on one turn so while I was able to generate the five steam points, I would up getting the result that burns off d6 Steam Points and does 2d6 S2 hits to the tank. I rolled five points, just what I tried to generate and did no damage. It still sat there and did nothing for a turn, so all in all not too bad. I lost two wounds because he marched a unit of Hex Wraiths through it and wounded it twice. I'm surprised he didn't keep doing it and he decided to go after my artillery which amounted to easy points for him. It the end it probably would have been better for him to not have gone after my artillery.
That being said, I found it to be just about as useful as it ever was. I like the drop in points to 250, but I think I'll have a hard time justifying it's inclusion in future games. Those 250 points go a long way towards helping the army do what the army does well now, locking and grinding. Sure it can do the locking thing, but not like it could and it is much more vulnerable now. I never was a huge fan of it even with the previous rules, but I'll try it out some more.