Just wanted to give some comments from my experiences so far - I have had a few test games and while not that experienced with the tau in epic I have played the system quite a bit (mostly as Guard).
Crisis - love the way they play. Perfect so far as I can tell. A little puzzled why the formation is more than the sum of its parts (I don't recall that anywhere else, but they seem worth it).
Fire Warriors - seemed a bit strong at first, but it did occur that without Devilfish they can't deal with vehicles well so making them specialist anti-infantry seems right. And I like the fact they're tricky to use to maximum effect by themselves.
Devilfish - not exciting, but as they should be.
Hammerheads - half as resiliant as a Leman Russ but twice the utility - I can live with that. I still think the Railgun AT seems a bit weak but they're useable. I would personally like to have the option of units up to 8.
Broadsides - seem to resiliant in CC - I would prefer a single better save so they were more scared of Macro weapons. 1 BS should not be harder to kill in CC than 3 Crisis.
Kroot - don't have any. Look alright.
Pathfinders - cool as - perfect.
Recon - don't have any. (personally would like to see the option of the unit size drop to match the Forge World pack as it will cost me £20 for a squadron, but thats less a balance and more practical thing)
Skysweep - agree with the cost change in 6.5.
Stealth - don't seem very stealthy to me. Also agree with the calls for Init 1+ as "Lone Wolves" should be more able to act under fire. Stat wise they're great.
Bonded team - invaluable.
Broadsides - Don't use. I don't like having the FW in a building and them standing outside. Think thats just me though
Commander - Both fair. (I only have enough Crisis for one formation so haven't used the Shas'el).
Crisis - great upgrade. Surprised Fire Warriors can't have them - is there a reason for that?
Ethereal - haven't used.
Fire Warriors - perfect.
Gun Drones - haven't used. I don't have a strong opinion either way on the expendable suggestion personally. I do feel they should be more a part of the Tau army than either 40K or Epic make it, as they are rarely seen (in my experience) as stand alone formations in either system. Stats look fine.
Hammerheads - preferred the old option of 1-4 @ 50 points each. I don't see it as game breaking in any way and it acts as a nice points filler/helps with spare models.
Kroot stuff - all looks peachy but I haven't played.
Pathfinders - again, perfect.
Skyray - at first it seemed expensive, but they are worth it.
I haven't used any of this yet - will add impressions as I get them.
Special Rules all work well, much better than the first version I looked at (4.something)
So thats another perspective from a (relatively) new Tau player. Hope you get something out of reading it, even if you disagree.
I also want to say I think the job on the list overall is fantastic - they are a joy to play and are a real change to the other armies I have used or played against. I am struggling against War Engines a little without fliers but at least they're still available.