AF L'espace Affaire (or biz class for the rest of us ) is a very good product. On the A340-300 you probably won't get the new seats (depends on the route you're flying, check the threads in this forum) and you'll find some seats to be a little beaten-up but nothing to write home about.

For me, the service level in biz is one of the best on transatlantic, food and wines are usually very good, attendants quite nice, etc... it beats any US carrier by a mile.