Jardin Nelson is a tourist trap, but for a tourist trap, you could probably do worse. We went on a Saturday around 2 pm, and the place was packed. The live music was decent Sinatra-style stuff, and the garden itself was very pretty..
As for the service, it was painfully slow, and I was annoyed when the waiter asked my (Indian) parents if they wanted the curry pizza. (They didn't.)
We started with a couple of salads for the table They were edible, but the dressing was really acidic and poorly balanced. In terms of entrees, everything was mediocre and drowned in way too much cheese.
I definitely wouldn't go back, but it wasn't the worst place in the world.