I think it's just stamina that I'm unsure on. Cherki seems strong enough to hold his own, and while he's not lightning quick and going to be constantly running in behind the defence I wouldn't say he's actually slow. Feel like he has the dribbling and technical ability to deal with the increase in speed and power in England, unlike Antony and Sancho. Neither aspect is something that would be an outright strength and bring up our base level (actually he probably is stronger than most of our #10's), but I wouldn't consider them weaknesses either. I'm just not sure about his stamina and ability to cover a lot of ground all match. Which might be an issue since Cunha seems to be the same.
I shouldn't do it to myself as I doubt we're signing him and I very rarely jump on the muppet bandwagon anymore, but I've got to say Cherki would be the most hyped I've been on a signing for a long time. Admittedly I haven't seen 'that' much of him so I could easily be wrong, but something tells me he's ready to explode and become a Ballon d'Or challenger in the next few years. I just hope he doesn't come to anyone else in England.