If it is a serious provider, like a cafe, or a hot spot, it is good to play
Whenever you use public wifi to access an account such as PokerStars, or your bank, it is possible that some villain is scanning/caching all the traffic on that wifi network.
If you only use your poker site login for play money, and use a different password from your other sensitive logins, then theft of your login access is not as serious. Of course, any info about you that is stored in your profile on that site is compromised.
In summary, NO - DO NOT USE PUBLIC wifi for any account logins.