First impressions:
Playfield art looks less chaotic than I thought it might.
On a game with a massive price premium, it's hugely disappointing not to have full RGB LED inserts in the playfield, or at least a few more of them. ST Premium and LE were over 3 years ago and they still haven't matched them in subsequent titles. Light show is pretty much non-existent at this stage.
The backbox LCD is really, really lazy. Almost everything is static and completely non-animated. Things pop up over the video / cityscape background, or move across, but virtually nothing's been animated beyond these very simple transitions. Very, very little original art. Not much information tying the modes or what's being shot to the video or stuff being shown on screen. Video clips from the shows seem very random at times. Huge improvement cosmetically over their red-sludge DMDs, but at this stage effort is seriously absent - and since they didn't say it was place holder, one has to assume it isn't.
Crane implementation seems rather lacking, especially when compared to its sister machine BMtDK.
Mini LCD (TV on pf) doesn't really seem to do anything yet except say POW! BAM! or KAPOW! No comment on whether it will.
The wheel mech with all the bits on looked absolutely enormous and very complicated when George held it up. Given all the QC, build quality and basic design issues with Stern lately, I'd be seriously worried about it functioning properly and durability. He even said it was the most complex thing he'd ever designed.
George also said at the beginning of the stream that they'd release new code every 2 weeks and wouldn't leave it alone until it was done ... if true, brilliant, but who actually believes that? Notable that he said that whilst Lyman had exited briefly.
Number of musical themes are fairly small in number ... the constant NANANANANANA Batman refrain will probably get old really quickly.
At the moment, BMtDK looks way more fun than this does .... not much evidence of flow or objective based modes.