I fully expected us to loan him and pay some wages, so a transfer-fee is really a big step forward, although it doesn't add much to this years budget (but who knows, if you've got good scouts you can get someone like Asensio for 3.5 ).
Good luck to Tello, I've always liked him. Betis is building a solid team with Tello, Camarasa and Leon signings, they are also rumoured to get Pašalić. If they can also keep Ceballos (probably on loan from Madrid) they'll be fun to watch next season.
Apparently we got 50% of future sale. At least some Sevilla media is reporting that. Nice if true as it's very possible he'll play well for them and they'll sell him for 15M or so in the future.
Considering he had 1 year left in his contract and we failed to sell him in last 2 summers I would say it is a good deal.
Now time to sell Douglas,Vermaelen & Arda