Really? He has been great for River ever since he appeared into the scene. He had a car accident few months ago and had severe injuries, but he has recovered extremely well and is back in form.
The problem with him is that he is really really small. Really. I don't usually go for the "needs to bulk up" argument, especially after watching Lennon do the trick with his physique, but this guy is really thin and short, I mean, even Alexis Sanchez looks like a monster compared to him (well, talk about hyperbole).
Tricky winger who can also perform as an attacking midfielder. I think he is really good and the Argentinian league is a little bit too small for him, but I thin either Italy or Spain would be better stages for him to perform.