I just read that a couple of weeks ago. I very thoroughly enjoyed it (but I very much enjoy Thrawn, period and have no problems with him being completely awesome - in my opinion, the real tragedy is he didn't win...!)
Notable for the first time, I think, EVER, that we actually get some scenes from THRAWN's perspective, which is amazing.
I am tentatively classifiying it as "close enough to Legends EU in counts as far as Bleakbane is concerned" - though I do actually have the short story in one of the Star Wars RPG supplements on which the first couple of chapters are based (Mist Encounter), too.