I think its kind of harsh, though I know your not trying to be. I actually liked all his Heresy Novels thus far. Some more than others.
I would say that some of his novels are quite radical, like Legion, or Prospero Burns. However, if my time in the Heresy series has taught me anything, its that I would choose quality any day.
Horus Rising, still such an awesome book, and I really don't think the series would have gone this far without it.
As far as his "radical" pieces, I've always noticed polar feeling from either or both Legion, or Prospero Burns. In each instance, it makes each legion appear over powered compared to the rest. But I once wondered how the series would be if Dan Abnett could have written about each legion. It would have probably been impossible, but it certainly would have had a certain flow. There are very few authors in the Heresy Series that should be considered consistent, and along with ADB, I would say Abnett really fills that spot.