The last two games I've played with my Tau have not been very much fun. I had a 1500pt game vs a Chaos Space Marine/Ork alliance, with a flying MC, a forgefiend, two rhinos and a battlewagon full of boys. The vehicles died quickly, and the ion head with markerlight support quickly dispatched the units that came out. It wasn't even close, and not fun for either of us I think.
Tonight, I played against 2000pts of Eldar. It was obvious my opponent wasn't having much fun..maybe because everything he tried to do I simply lit up with markerlights, took away cover saves - conceal wasn't very useful - and then blew things off the table. SMS is a pretty good weapon against Eldar troops, and tank-hunting missile pods work well against their tanks.
At the end of the game he had 2 models falling back, and a Farseer on a bike. I had lost my Kroot, 6 Crisis suits and 2 Piranhas. It wasn't even close. He said "My first game against the new Tau, and hopefully my last." Sigh. I felt bad.
Pretty much playing against Tau means putting models on the board..and then picking them back up again.
It isn't hard for Tau to completely dominate. Once they get a bit ahead, it's hard to come back just due to the sheer firepower.
I was talking with a few other players after the games and some of them agree that Tau can be very..well I like the term "turn-key"..it does not take much thought. Just delete units in order of threat. Other people really enjoy playing Tau, even when dominating. I almost want to try less-optimized lists just to make it more challenging.
Thoughts? Ideas? Tau aren't unbeatable for sure, but they are really, really good.