This was our third french restaurant we visited while in Vegas, and boy was it packed! Fortunately we had reservations so we got through with no delay, but I would make sure you get reservations if you plan on dining here.
Mon Ami Gabi has a simple menu really - it's steak and frites. I got what they said is they specialty - the filet and frites. We had the escargot to start which was good, and the baguettes were excellent as expected. The filet was perfectly cooked and delicious, and the frites were also great.
My girlfriend wasn't in the mood for steak and ordered scallops, and she was surprised how good they were. So even if you aren't in the mood for steak, you have another option. :)
For a simple casual french style steak, this is a great option.