Teaser video for the Militarum Tempestus is up on the GW site here. So my thoughts on the TM? Looks like a mini-dex for Storm Troopers/Arbites. Perhaps a way of including ST's in any Imperial army; so Inq/GK's/SoB get there Inquisitorial ST's/Arbites back.
As for the models that have leaked, the ST models look OK, though I'd rather use helmets than berets on these guys. The Taurox looks like they started with an Ork Battlewagon and worked backwords to de-orkify it; not a fan. If the rules are such that I want one, I'll build something from scratch or convert something. As for the Ogryn/Bullgryn? meh. I have a box of WHFB Ogres that I bought long ago that I'll convert to fit with my Vostroyans