1. Tau shoot. Their most basic (pulse rifle) and most powerful (rail gun) weapons are top-knotch, but their special weapons (Plasma, missles, etc) lack the punch that is the standard for most other armies. Of course shooting 6 strength 7 missiles instead of 3 strength 8 missiles might not truly be 'weaker' in that it is less effective, the opposite is usually the case.
2. You don't have two pages of wargear to worry about, you don't have to balance shooting with close combat, everything is reasonably solid, it's pretty newb friendly.
3. Tau can be booring, this is their drawback, you shoot, shoot, then shoot some more. Their strategy relies on applying the correct amount of firepower to neutralize the correct target, instead of rushing forewards madly to bust heads, or pounding the enemy into submission with as many big guns as you can find.
The other side of it is seeing the look on your opponent's face when his charge fails terribly because you've got fourty pulse rifles pointed at his assault specialists. Or when you've removed his carefully hidden and 'well protected' artillery battery with a crisis suit. Or when you've lead his angry Chaos Dreadnaught on a wild goose chase across the board with your Stealth Suits because he Blood Raged and was forced to move towards them instead of the objective (that happened in my last game, it was great sport, at least for me and the Stealths).
