I play tau myself. Just got back into the hobby a few weeks ago. Havent played since 04'. 5th much different then 4th?
5th is all about mobility and capturing objectives instead of victory points.
Tau... well, their Troops (the base for 5th edition gameplay) suck, to put it clear. Too expensive, low stats, and incapable of defending anything. They are only useful inside their vehicles while sitting close to an objective. Any competitive Tau army nowadays is all about 9 Crisis suits, a commander in a crisis suit, his bodyguards, as many tanks and Broadside suits as possible, and a few fishes in a can (their Troops), which is kind of boring.
About competitive gameplay... it can get to 3.5 intense-like optimization debates. For instance, Imperial Guard need 3 Vendetta gunships (airships with a lot of Twin linked Lascannons) in tournament lists, a Manticore artillery tank, a Hydra flak tank squad and whatnot. All armies have 1-2 competitive options, then the funny lists.
@Soundwave, I like your white; smooth looking and even coverage. Do you mind posting how you got it? it's a color I avoid for anything larger than SM helmets because of the difficulty. Also, yes, meta is all mechanised armies. I usually field 6 Razorbacks, 3 Venerable Dreads and 3 Dreads (all of the dreads wth S8 TL Autocannons) because walking is for poor, mobile cover Guardsmen *cough* expendable troops
BTW, I play Grey Knights (no, not bandwagoning, I have a lot of the old metal ones, needed to clarify as they are now a gouda level army), and just sold away all my Blood Pact army (traitor Imperial Guard)