Aside from the HQ section, the Tau's Fast Attack is the most heavily populated section of the new codex. And amazingly, of the six units available, the worst of them is still solid enough that you won't get laughed at for plunking it down on the table.
But before we get to the Vespid, let's start at the beginning. Pathfinders are the breakout hit of the Fast Attack section, basically for one reason; the removal of the 'Devilfish tax'. The mandatory Devilfish never made any sense for Pathfinders, since it was a vehicle with no firing points transporting a squad armed exclusively with heavy weapons, and given the hit basic transports took in the switch to 6th Pathfinders were even harder to justify given the giant, tank-shaped anchor around their necks. As soon as you take that away, however, what you're left with is a 4-10 strong squad of models, which cost 11 points each, and which carry possibly the single most useful support system any codex in the game has ever seen. The markerlight still boosts BS like it used to, though it's no longer capped at BS5, but even more useful is that for a mere two markerlight tokens you can give a firing unit Ignores Cover for all its weapons. Tired of dealing with Jink saves, KFF's and Plaguebearer's going to ground behind Aegis lines? Throw an average of 44 points of Pathfinders at them and blaze away!
Pathfinders do come with more than just markerlights, though. As before, they still have their carbines, which are now Assault 2. It's an improvement, but you'll almost never want to fire those over markerlights. They also have two alternate weapons available, the old rail rifle and the new ion rifle. Neither are cheap (the rail rifle is 10, the ion 15), but they're not bad for their price. Both have 30" of range, with the ion rifle functioning as a Rapid Fire missile pod that can be overcharged into a S8 Gets Hot! small blast weapon, and the rail rifle getting bumped clear up to AP1. Compared to anything else, these would be amazing for their cost, but the markerlight really is just that good that it's worth foregoing them. They also have a trio of unique drones available, Recon, Grav-inhibitor and Pulse Accelerator. The Recon drone is the most expensive, costing almost thirty points, but it offers a homing beacon and positional relay, useful tools for Tau commanders who want to play with deep strike and outflank units, and a burst cannon for good measure. It can also be mounted in the turret of a Devilfish, where it continues to put out its two system signals, but you lose the burst cannon's use. The Grav-inhibitor comes with a Gravity Wave Projector, which reduces the charge range of a single unit by D3", but since you have to nominate your target at the start of your enemy's Assault phase, and it only functions if that one unit charges the Pathfinders themselves, it's not as strong as it could be. And the Pulse Accelerator drone increases the maximum range of pulse weapons by 6", meaning Pathfinders would find themselves with 24" pulse carbines. The drones are interesting, and can be fun to play around with, but you won't be losing out on anything major if you decide to leave them at home and run your Pathfinders bare-bones.
There are some other options, like EMP grenades and bonding rituals, and a Blacksun filter that's literally useless unless you buy one of the other guns, but there's not much to be gained from those other than to decrease the number of markerlights you can bring along. If you want to field them as a special weapons squad you can, and they'll do well enough, but I just have to say it again; 11 points per markerlight!
Now, the Vespid. In the last book, they were one of three units that there was simply never a reason to take unless you had an unnatural love of the models themselves. Thankfully, this has changed. The Vespid got a boost to their armour, an extra 6" tacked on to their neutron blasters, and a bit of a points drop all around. Since their base LD is 6 you'll basically always buy the Strain Leader, though, so the 72 point cost is a little misleading. Aside from growing their squad, Vespid have no options.
I still don't think these guys are great, but they're far less terrible than they used to be. No more losing markerlight utility if the strain leader is dead. No more 5+ saves and 12" guns. The Neutron blaster is a serious bit of anti-MEq hardware, and now it's in the hands of models that can take care of themselves. T4/4+ with Stealth(Ruins), Jump troops with Move Through Cover and I6/Hit and Run give Vespid plenty of options once they're on the field, and not a bad amount of protection.
Unfortunately, at the end of the day these guys are a pricey answer to a question Tau don't really have to ask anymore, namely, 'what will I use to kill MEq units?' There are a several very solid AP3 weapons in the game at the moment, plus the usual ridiculous amount of torrent shooting available to drag them down through weight of numbers. Vespid are only good at hunting Marines, and that's just not something Tau commanders need to pay a premium for. They've definitely gotten better, enough so that fielding them isn't a waste of points, but generally speaking you can find other units that can handle the one and only job Vespid can handle just as well, plus do other things as well.
Last up in this first look at the Fast Attack section, we have the humble drone squadron. Drones have actually increased in price, which is a little much given that they gained Assault 2 and lost ever being able to score or contest. Given that 5 of 6 missions in the rulebook revolve around objectives, that's a serious black mark on their file. However, the drone squadron picked up something that might well make up for this; for free, any gun drone can be upgraded into a shield drone or a marker drone. That's right; T4/4+ Jet Pack infantry with markerlights! For three points more than a Pathfinder, you get way more mobility and survivability, though you do lose a point of BS.
The standard gun drone squadron is likely going to lose out quite heavily to the marker drone squadron, though I don't imagine most players will take more than one. There are a couple of tricks to boosting their BS2, such as adding in a Commander with drone controller or using the Fireblade's single, BS5 markerlight to get them on par with Pathfinders. They're a little too expensive on their own to replace Pathfinders, outside of special builds like air cavalry cadres that want everything as mobile as possible, but a unit of these and a unit or two of Pathfinders isn't a bad idea, and the drones will likely keep you in markerlight tokens far longer than their on-hoof counterparts. Survivability or independence; which do you prize more?
So, that's the infantry choices of the Fast Attack section. It's a mark of just how great a deal Pathfinders are that 18 point MEq killers and Relentless markerlight drones have as much of an uphill fight as they do to get onto the field. But at the same time, the Pathfinder team isn't so good that it's just a reflexive 3 x Auto-Include, which is nice. I don't mind one unit being a bit better than the rest, so long as the rest are still good in their own right, too.
Next up, the vehicles of the Fast Attack section!