Here's Mandalore Gaming's review of Warhammer 3 on launch:
Summary: it's a great game for fans of the series, with lots of cool races and neat mechanics. However, there are serious issues - particularly with the new siege rework, though the normal Creative Assembly bugs and glitches at release still make it in.
For me, it's an obvious must-have and I'll be playing it on release... but I'm keeping TW:W2 on my main gaming SSD until the full Immortal Empires map comes out in 3-6 months' time. I'll also probably wind up modding a few of the more obnoxious elements I've seen in the preview videos once I get my head around the core game balance.