Tevez on loan+rights to buy is a really good transfer. Kinda like Ronaldo joining Milan in 2007.
At least for this half season and from today's point of view it's an excellent transfer. Milan can afford resting key attackers for CL and not even feel it.
Now, in 2007 Milan went all the way to winning it and having Ronaldo to replace Inzaghi for serie A did them good both in Europe and in Italy (strong finish which gave them a CL spot after being out of top 4 for most of the season). I don't know how far will Milan go in CL. It will depend a lot on the draw. But in serie A Tevez won't hurt to have even if Milan are eliminated early in Europe.
It's for next season that Milan will have to think twice if they should buy Tevez or not. Lots will depend on the finances, on Tevez's attitude and Tevez's performances this half season.
City should negotiate a good deal. Milan do need Tevez right now. They do need a top striker who'll allow Zlatan or some other striker get some rest. City should know that and negotiate a nice little loan+rights to buy for 30m eur deal.
yep, it could go either way. I myself wouldn't want Tevez bought outright as I have my doubts about him - not so much character issues but overall intelligence on the field and how he would fit with this Milan altogether; seems a bit too much of a solo player, the opposite of what we lost with Cassano, but will see.
Other than that, with an unforced option to buy, Milan can't lose much on him as they will have time to kick his tires and check his teeth - pun intended

- and it's not like there are many top-players to choose from anyway.
If he fits in well, he would be of immense help to the team even w/o CL, no doubt about it. But wouldn't expect Milan to end up buying him unless he sets San Siro on fire and costs no more 20/25 in the end of the day - it seems they want a free loan + option to buy for 15/18 mil, while paying the rest of his wages for this year.
time will tell.