I lied, stayed up and got all three unlocks.
Mini sentry is good for ambushes, just run round a corner, drop it and then it and you can attack anyone chasing you (it builds very quickly). You only get one mini sentry at a time and it stops you building proper sentries. Since they're 100 metal if the first dies you can put up a second which is useful as you can't repair them.
Shotgun upgrade is kinda cool for when your sg gets owned or you've had a few kills with your sg and want the crits as it seems to have no cap on the crits it can save up (two crits for a sg kill, one crit for an assist).
But while your sg is up you're stuck with a crap shotgun that has 3 shell magazines :/
The wrangler covers your sg in a transparent red/blue ball shield and has a red/blue laser beam pointing out from it that you can target around the place. LMB = bullets RMB = rockets. NO limit on range it seems so you can shoot a sniper back from across the map if you can get a good line of sight.
The glowing laser beam and shield lights your sg up like a beacon though and ideally you need to be near your sg so you're targeting things it can hit. otherwise you might be trying to target things round an obstacle that you can see but your sg cant :/
The packing ability where you right click and then can transport your buildings is awesome. You can rank up a L3 building disp/sg/tele somewhere safe (just outside spawn) then walk out and stick it where its needed. Rebuilds itself quickly. Excellent for advancing teles in capture point maps. None of the garbage of having to trash your teles and rebuild from L1 again.
Incidentally. Packing seems to automatically disable sappers. Pack anything with a sapper on it up and the sapper is removed. Your building will still have lost whatever health the sapper took when you unpack it but the sapper itself will be gone. Interesting save if you need the building to stay alive but don't have time to remove the sapper.
**Update: packing a sapped building now causes the sapper to reappear when you unpack it but now it's impossible to remove, you can use metal wrenching and repairing the building but it will not come off. Sapper disables and eventually destroys the building as normal.
If you die while carrying a packed building then both you and it die and the killer gets credit for both kills.
The engy has TWO taunt kills now. Possibly to make up for it being the last bugger to get any.
The Frontier Justice kills by clubbing someone with a guitar and a humourous musical twang.
The Gunslinger you pull a ripcord as if starting a motor in the gauntlet and the fingers spin around like blades which are then thrust into someone/thing.