The problem is with the PSK variety, mainly that it's susceptible to offline dictionary attack: about 5% of actual WPA2-PSKs can be easily guessed [1].
There is stuff in the works to fix this though. My favorite is EAP-PWD [2]. It's resistant to offline dictionary attacks, it has perfect forward secrecy and it's already supported by Android. Basically, it's what WPA2-PSK should have been.
In the mean time, if you're security conscious just set a long random PSK or configure e.g. EAP-TLS. Both will give you strong security against pretty much any attacker.
