I agree that Aguero is the better player. However, I believe an Italian would perhaps have more passion playing for an Italian club as opposed to a non-Italian player who comes to us as their 3rd choice. Rossi is fast, clever and a good finisher. He's better than what we've got just now at least.
As for people slating Rossi with regards to choosing Barcelona over us, I ask the question: Who in their right mind wouldn't? I'm sorry but I'm a Juventus fan and if I was a professional footballer looking to progress, if everything was as it is just now, I would pick Barcelona.