Obviously Gundogan and Kroos would be ahead in the list, but Rakitic is not a bad consolation price. Forget about the 40M buyout, he won't cost 40M.
The biggest concern I got back every time I mentioned Rakitic for reinforcement, was "He's too offensive, we already have offensive midfielders". Well, Rakitic is twice the defender from the midfield position than Xavi is at this point. Rakitic is averaging 2 tackles and 2 interceptions per game. This is more defensive production than Barcelona get from Xavi and Iniesta, combined. It is also more than Jordi Alba averages for La Liga. Rakitic has also played as CDM for Sevilla on occasions. Obviously his defensive contributions are not the issue.
People might want to look at his 79% passing success and try to raise concern. While this is a far more valid argument than the defensive one, we need to take into account that Rakitic is playing a very offensive role for Sevilla out of team necessity. Sevilla is a direct playing team, and a team that likes to defend and counter. More often than not, Rakitic is leading a 3 or 2 man counter with his passing options being low efficiency ones. He does not have the luxury of having a Barcelona system where passing options are high in efficiency and he does not have the luxury of simple passes to prop his percentage numbers up.
Rakitic is obviously not at the talent level of Iniesta, or Xavi in his prime, and like I said, Gundogan and/or Kroos are the far better and superior choices, but he is not a slouch. He's got vision, has 16 assists this season. He's got technical talent. He can score, has 12 goals this season. And he has excellent defensive contribution. He is a good two way player, and IMHO definitely capable of contributing for Barcelona.