The kit is very nicely designed. The pieces all fit together smoothly, though due to the big-gribbly-monster nature of the set, it isnt always clear which mutated rat head goes where so I had to do a lot of dry fitting. Some of the seams are hidden away cleverly, but some are fairly obvious. Wherever I could, I used a file to try to blend the edges together a little so when I paint it, they shouldn't be too noticeable.
As you can see:
It is indeed a big, rat-ish, gribbly beast of doom and does exactly what it says on the tin.
Now the negative points. Apart from two variant arms, a couple of variant rat heads that go on top and a different weapon piece on the main head, there are NO extra pieces in the set. No bits or extra things. Whilst it is possible to construct a second HPA using the variant pieces, the two models would be in exactly the same pose. The model has zero wiggle room for making it look different without taking a saw and green stuff to it in large quantities. Each piece has to fit 'just so' or the model wont go together.
Overall, I would say 7 out of 10. Its big, scary and an abomination but there is no versatility in the kit.
Large blocks of high S troops will take it down though. Large blocks of troops > big monsters.