The interwebs are full of doom and gloom.
Here's my thoughts based on what little we've seen.
Tau are the Canadians of the 41st GrimDark Century.
They get a long with everyone (except the Nids) are are mostly ignored much like Canada.
However, I'm intrigued and cautiously optimistic about SnapFire in the pre-assault phase.
Also, Assaulting is no longer twice as good as shooting. While power-armor fan boyz will cry to the Emperor about it, it's balance and makes Assault armies as good as shooting armies, not better.
With the SnapFire/Overwatch combined with removing casualties from the front first, there is actually a chance to stop an assault from happening.
This, if you'll forgive me, is accurate, in the trenches of WWI your opponent's had to charge in against a withering fire. The Germans didn't just saunter over and start punching Dough-Boys without enduring some bullets in retaliation.
I've put together a Tau Gun-Line army in hopes of 6E.
While people are crying QQ allies is the broken!
You're making major sacrifices to take another HQ in the hopes of getting some tool to improve your army.
It's a substantial trade off, which it should be.
I for one will be taking some Terminators over 1500 cause hey, Tau need it baby!