As an Inter fan personaly i think he did pretty well in Europe even though we didn't go far enough back then, part of it had to do with luck (who remembers that fight we had with Valencia and red cards that our players got).
Anyways, I used to say to guys here that Mancini will do pretty well with Man City before he stepped a foot here and people here had doubts about that. Mancini is young but from the very beginning of his managerier career with Lazio he showed that he's "a winner" and thats something you can never buy or get easily. Every single season with every club he won trophies (even with a bankrupt Lazio who everyone wrote out yet he won the Italian cup and did really well with them in the league race).
You guys should have faith and don't do what Chelsea's owner is been doing, firing and hiring managers almost every season, instability is extremely bad for any team.
I said here in this forum a couple of years ago, have faith in Mancini and you won't regret it on the long run (even if you had a few falls every now and then). We used to buy the best talents in the world (ronaldo and co.) in the past yet we suffered for many years because of that instability with our managers (we used to hire and fire every season) untill we got Mancini and for the first time we tested trophies and stabilities. Now we're going backwards with the same instability problems that we had since the early 90's and we're doing shit domesticaly.
Hope you don't fall into the same trap !