I'll buy this, because even if it's broken on release, it will get patched eventually. It will also get modded to high heaven, making it a worthwhile investment for replay and longevity value.
Plus, it'll have Orcs and Goblins in it from the start, which means I won't necessarily need any DLC unless it's truly worth it to be able to enjoy the game from the start.
It'll be interesting to see what they do with magic. Will it be battle only, or will there be magic usable on the strategic map, ala MoM as well? Toned down from MoM levels of course, since it's not a game completely based on magical shennanigans, but some strategic level spells will hopefully be available for all the magic type. I'm really hoping so anyway, as it was something lacking in WHFB. It always suprised me that there wasn't a pre-or-during setup magic phase or something on the tabletop version. Hopefully with an actual strategic layer to the game in TW:WH (even the acronym is weird to type), magic can be shown in ways that it hasn't really been shown to function in the game mechanics before. In lore and stories, yes, but never really in a game AFAIK.
Oh, and I can't wait for the sound effects of the 'shroomed up little goblin Doom Divers as they go sailing all over the place. Wheeeeeeee........ SPLAT!