Check it all summarised here with the pretty new pictures from White Dwarf and confirmed rules in the comments section.
The big thing of course is still the Riptide - a very solid statline (T6/W4/2+/5++), potentially W5!, and for the cost of an old upgraded hammerhead, you're getting that lovely Ion Cannon. That massive thing could be replacing a lot of Crisis Suits it seems - yes it really is Elites.
Here's a small taste:
Skyray can shoot and ground and air targets (one assumes at full BS).Stealthsuits are better at overwatching shooting at BS2Special character is "like" Chronus for tanks. Tank Hunters. Potential cover boost. Tank can overwatch. Hammerhead roughly 160-170 WITH character.Special Pathfinder - Nightstrider.
Lots of the little things still missing but we're beginning to get a better picture of how this codex is going to turn out. The fliers are still sound pretty blah but there are enough skyfire options it sounds like in the book (that don't suck elsewise) that shouldn't matter much if this is true.
Really looking forward to adding some new Purple Tau to the Greater Good Force of Fashion Police :)!