Howard Hamilton at The Soccermetrics blog, summarising an FFP research paper by Thomas Peeters and Stefan Szymanski:
The authors finish the paper with two claims: first, FFP represents a transfer of rents from players to owners with little to no benefit to consumers (i.e. fans). Therefore, in their opinion, a legal challenge to the rule under European anti-trust law could be successful. Second, a salary cap that more resembles that of North American professional leagues would satisfy the goals of wage spending control and competitive balance without raising barriers to success of the smaller clubs. It’s a nice goal to have, but I have no confidence that such a cap could be implemented in an European football industry as currently constructed.