Anyone who says the FA MAS is crap has never used one.
The main problem I've found with them is the fire control system is just way too complex, one lever to switch between burst-fire and full-auto, another to switch between safe and fire, plus the sight adjustment is quite complex as well, and in addition on the G2 model the mag release is really hard to operate.
Once you've got a mag in, cocked the thing, got the sights adjusted and got all the levers pointing the right way, I'd take one over an AUG or an SA80 any day of the week. (Remember we are talking about the people who came up with the Citroën cars with their insane controls).
They are really accurate, and they do work reliably with NATO ammo (fluted chamber) contrary to the comment above. Plus they are really easy to take apart and clean. Recoil is a bit heavy compared to an AR-15 but they do have a proper buttplate so it's not a big problem.
I wouldn't shoot one on full-auto though because the mag change is a #####. Better balanced than an AUG or an SA80 though.
I've always though the FA MAS is the best bullpup, mainly because of the trigger pull, it is heavy and creepy like all bullpup rifles but the trigger is far better shaped than the stupid straight backward pull of the AUG, or the "squaddie proof" trigger on the SA80. Which means it has a more predictable letoff than either of them, and trigger control is far better.
The iron sights are also by far the best of any bullpup rifle, and a fair number of regular rifles, however it is very hard to mount optics on which is a big downside.
They're also not expensive, the 20 or so guns imported into the US go for insane amounts of money but they don't cost that much if you want to equip your Army.
I tried an FS2000 the other day and it seems to me to be basically a more complicated version of the AUG, the trigger is just as bad.
Personally I think the FA MAS is the best bullpup rifle.