Gunslinger has been changed to effectively allow the Engineer to expedite the entire build process and make all of his buildings somewhat expendable. It's not all that different from the current Gunslinger build, really.
Frontier Justice fires slower and reloads slower. It has a larger clip size compared to the current one, yes, but when you exhaust that, your refire rate is horrific. It's also comparatively worse in close combat due to its firing rate, but with the revenge crits mechanic, it encourages one to aim a bit more carefully when unloading said crits. Don't ask me why- I don't know- but having tried it out last night, it seems to work splendidly.
Ambassador has been changed into a hand cannon. Tremendous damage, but only one shot per clip and the reload/refire time is enormous. If you hit with that one shot, you will take down pretty much anything at close range (noting, however, that it CANNOT one-shot anything from full health at close range unless it crits), but you're screwed if you miss. I need to remember to remind Gamemaster to nerf it against buildings, though. I believe it can currently take down a minisentry in one hit at range, which is problematic.
L'Etranger is now a stealth weapon. You sacrifice firepower in a very large way to gain silent decloaking. Not sure why the lack of disguise kit is there, though. That strikes me as odd, though I could have sworn there was some kind of roundabout reasoning for it.
Saharan Spy is, I think, meant to have +10% movement speed bonus (not minus).
On a somewhat completely different note, as mentioned in passing above, several of us had the chance to try the mod out last night. It was incredibly fun, but it does need a few tweaks. Offhand, I know Gamemaster will be nerfing the movement speed on Natascha's in-mod incarnation and trying to figure out why the Equalizer has a Shovel kill-icon.