IMO it's highly dependent on player build. Based on what I know, 3-2 is most effective where you have high OD from 1-3 and high SB in the posts (because of increased help defenses). If your opponent has a team specifically built for it, there's not much you can do without having players with good enough skills to break their defense. Outside offenses will be shut down, balanced focus will still have your players matches against the best inside/outside defenders depending on where they shoot (it's particularly great at shutting down Patient), and if you run inside offenses, if your guard's DR or PA isn't high enough to break their perimeter defense, you can't pull off LI/LP.
On the other hand, if their player has a weak link (eg: lower OD at SF) then it's a potential weak link tjat can be exploited. But even then it's harder to exploit then if it was M2M, since unlike M2M, you won't know which attacker will be up against which defender.