The former Liverpool star believes that the Gunners have landed one of the best players in Europe, although he is still to be convinced that they are ready to compete at the top.
The playmaker completed a big money move from Real Madrid on deadline day, a deal that smashed the north London club's transfer record.
While Hamann is sure that Arsene Wenger has acquired a player of the highest caliber, he does not believe the Gunners can now be considered an automatic title contender.
"With the pace of [Theo] Walcott, the trickery of [Santi] Cazorla, the physicality of [Olivier] Giroud, [Ozil] will create a lot of chances for Arsenal and I think he's a top, top signing," he told Goal.
"Whether it's enough for them to challenge for the title, I'm not too sure, but it certainly is a step in the right direction."
Hamann compares Ozil to Spain playmaker David Silva and expects the former Real Madrid man to make the Gunners a far stronger team as they look to challenge for honors in the 2013-14 campaign.
"I think he is a fantastic player, I think he's a fantastic signing for Arsenal – I think he'll improve the team no end," he added. "He has more assists over the last four or five years than any other player in Europe and he can create and score a goal out of nothing - and I don't think there are too many players of that caliber.
"David Silva played a similar role at Manchester City when they won the league and I think he's a similar type of player who's always available, rarely gives the ball away, and you know, once he's got the ball, that something's going to happen."