Wow, more people whining about Tau.
Mono Tau is not that powerful, if you or or opponents think it is, play better opponents or make it ultra casual.
The simply truth, Riptides aren't that great. Supported Riptides are. So, if you have a Buffmander, Many Markerlights, or allied Psyker they become much more powerful. Alone, Riptides aren't that great and
IA riptides have a relatively low damage output for their cost.
Just to illustrate my points, here is the Feast of Blades Breakdown. These are some of the best
40k players around.
http://www.torrentoffire.com/1745/feast-of-blades-invitational-by-the-numbers
Mono Tau had a substantial losing record. Tau/Tau did better, Tau/
SM, did even better, Tau/Eldar did better yet, Eldar/Tau even Better, and Pure Eldar dominating the field. Three of the bottom six players were Mono Tau.
Moral of the story, just play MonoTau, there are plenty of counters and its not as
OP as you think. Things get crazy when you bring Allies into the picture, this is where Tau is getting a bad rap.
As always, make sure you and your opponent know what kind of game you are playing. The Beer and Pretzels league with a fluffy army and upgrades just for the sake of having them don't mix well with competitive players and builds. But, if you think that Tau are too powerful to even be on the table with the other codexes and need to be gimped to the asnine levels some on here have suggested either you don't understand the game, or are playing the wrong style of game with your opponents.
And as tough and as bad as Tau are, Eldar are far far worse and more powerful yet get less hate because people erroneously hate Riptides more than Eldar Jetbikes.