I honestly believe the "tiki-taka" is the best tactic to use in world football. The problem that Spain and Barcelona have become is that it isn't the system or the style but the players. In Barcelona players pass the ball around but there is no movement or no runs in behind the defense. Barcelona players like to play in-front of the teams defense and it makes the system look stale. You see under Tata (obviously he's gone) how the team is playing with vertical play and making more runs behind the defense. That is why last season Barcelona have scored more goals in the first half of their campaign. People also have to realize that tiki-taka needs one extra component to make it useful. Total football. Players not having a base position.
This is why it is so easy to park the bus against the tiki-taka. Remember the goals vs Madrid in the 5-0 win? The first goal who scored it? Xavi and I think the commentator said it best "Xavi in the center forward position." Now a days its usually just Messi and Cesc in the box only, thus making it easy to mark them. Making a surprising run into the center of the box can unlock even the tightest of defense now because the two CB's are occupied. Now someone is open. Look at the Milan game, in the 1st leg there was no one in the box and the Milan CB's had a relatively easy night. In the 2nd leg Villa occupied the two CB's and that caused them problems and that opened up space and we won the match 4-0. No movement causes the system to look really weak, and Barcelona became so dependent on Messi that they don't even look to move around much. For Spain, they just lack a striker. If they get a proper striker then Spain will look like the Spain of 2008-2012.
The problem is never the passing in the tiki-taka or the rhythm of the match. I prefer fast tempo, but slow tempo can also work as effectively if there is good movement. Slow tempo will cause the defense to lose concentration for a split second and with-in that second any movement or surprising run into the box can be picked out easily by the quality midfield Barcelona has. It is the movement into open spaces that team Barcelona and Spain lack badly. Bayern's total football (when they had jupp heynckes) is great but if you pass around them and make good movement you can pull out the defenders/midfielder out of position and open up space. Sorry for the long post lol. But people are not looking at what has really happened with the Barcelona of then and now. They have become tired and lack movement that is why rotation is so critical in a side like Barcelona. They play at least 2 matches every week for 10 months straight.