KoW gives a good clean game. It is pretty abstract - so can take a game or two to get your head into the tactics.
Yes - 'clean' is bang on. And the rules themselves are extraordinarily clean - editorially - by wargames standards, which makes them very easy to use.
You're quite right about the abstractions too: I think you have to interpret things like the routing of a troop of Orc 'skulks' shielding the advance of a 'morax' regiment as representing the 'job done' scattering of skirmishers rather than a set-piece fight. Once you see the narrative in these sorts of situations, the tactics make more sense.
On a similar topic, the new rulebook is really great. The convenience of all armies being together is great and we had a fun time with the new Siege rules as our campaign finale.
We haven't tried out siege yet, but will aim to do so soon. I'm also itching to try out a legendary battle, though I think our regular two-a-siders have often been similar. But legions of trolls sound like great fun!