Provided that the conditions on the obligation are sensible that seems an ok deal.
I'd rather take the chance on him on loan than blow our money on Belotti or Muriel or an older washed up player on high wages. Given that Ronaldo has left so late in the window maybe this is the best we can do now, then regroup and plan something better for next summer.
I like Kean and think he could develop into a good striker, he is only 21 after all plus being homegrown is a big plus. His movement in the box and willingness to run in behind bring something different and could be a good impact sub. But he is still very raw and has lots to work on. If he doesn't progress it's hard to see us wanting him here in a couple of years.
I am slightly concerned about going into the season with 3 inconsistent strikers though in Morata, Dybala (mainly fitness wise) and Kean, plus the completely untested Kaio Jorge. Suddenly winning the scudetto back and getting a decent run in Europe seems like a bigger challenge.