Indeed. Those were 2 months to forget for him. But before that he was, imo, their best player and now he scored on his last two matches (he didn't play against Santander iirc) so his crisis might be behind him. We'll see soon.
Suns' main comparison was between Eto'o and Ibra though and in this case, although certainly not by much, Zlatan is proving to be a better player for Barca than Eto'o is for Inter.
Eto's record isn't awful (10 goals on 26 matches) but he's not playing well and more often than not he's being outshined by Milito, Balotelli, Sneijder and Pandev, who all have a better record than Eto'o (goal+assists compared to time spent on the pitch).
Deal for deal though, it's pretty obvious that Inter got the better of it. They got Milito, Eto'o, Lucio, Motta and Sneijder with the Zlatan money. On the other hand Barca splashed 49 million just to make a simple player swap and so far Zlatan (although he already scored 15 goals) is not proving to be more useful than Eto'o was.