S-35s were pretty decent tanks for their timeframe and had good armor and reasonable speed and maneuverability. It's gun was probably better than what the Panzers had (at least until PZ3s got upgraded to 50mm). The French just didn't really have a good idea as to how to use them, spreading their tanks quite thinly across their formations and not equipping them with enough radios. The main *integral* drawback to the S-35 (and a number of French tanks of the time) was that the Commander was also the gunner and had to narrow his focus while firing at the immediate threat, thus possibly losing sight of the bigger picture. Also, iirc, the Somua had a big-assed hatch on the back of the turret that, while being opened, allowed anyone nearby to easily throw 'splody things inside or take pot-shots from further away.
