Tau receive a flyer and data sheet for it. Fast attack choice. Armor 11 all around. Non tau pilot. Looks like a manta ray flying backwards. Bs 4 super sonic. S6 ap4 missiles. Off center gun heavy 6 str 5 ap 4 twin linked or single small blast Str 8 ap 2.
That's not a bad look, actually.
First, the placement is nice; Tau don't have a lot competing for the Fast Attack spot. If this thing had gone into Heavy Support it would have forced some pretty serious tradeoffs, particularly given its loadout. The AV is good, not great but notably better than the Barracuda, and BS4 standard is the least one should expect. The lack of hover might be problematic, but it hasn't stopped any non-Marine flyers from being dangerous, so it's not a huge problem. The hull looks promising, though of course without a points cost or knowledge of the types of options available (primarily, can it buy a disruption pod?) it's impossible to say whether this will be a good kit or not.
Unfortunately, even without a points cost, one thing is obvious; this flyer is going to have very little to offer as a flyer-hunter. For codexes without flakk missiles (read, all of them but Chaos Marines and Dark Angels) the best answer to a flyer is another flyer. Yes, there's the quad gun and the Icarus lascannon on the Aegis, but those are single guns, with limited arcs and rates of fire, vulnerable to being destroyed by enemy forces before any flyers turn up. If you really need to deal with another army's flyers, you need one of your own. And whatever this thing ends up getting called, it's not going to do the job.
Heavy 6 is nice, but at the end of the day a S5 gun is too weak. Relying on glances to deal with most of the flyers in the game is not a solid option. Worse, this leaves it incapable of threatening the two most common flyers, the Imperial Guard Valkyrie/Vendetta and the Blood Angels/Grey Knights Stormraven. It's S8 option would work better, but of course you can't fire blasts at flyers. Which leaves it with its missiles, and at S6 the odds are actually even worse for dealing with AV12 than trying to take on AV11 with the main gun; at least that's Heavy 6, while these are presumably one-shot weapons, like every other missile in the game. Worse, every other flyer in the game has better weaponry than this thing, even those like the Dark Eldar with tissue paper AV10 flyers. This means that not only will Tau flyers struggle to deal with their counterparts, but those flyers that easily shrug off S5 will be more than happy to come back at it with S7, or 8, or even 9.
Like I said, without a points cost it's impossible to say whether this thing will be useful or not. At 50 points, it could fill a valuable ground-attack role; with a flyer's speed it's not hard to get into rear armour arcs, where S5 Heavy 6 can really ruin someone's day. But anything more than about seventy-five points is simply not going to be cost-effective for what this thing can do, given how expensive Tau units are relative to their utility already. The Piranha is overcosted at that level, and at least it gets a melta gun.
So. Here's hoping either this flyer is cheap-as-free, or that the guns are a lot better than what's been reported!