I think it really depends on the tyoe of birth you want. though i firmly believe the more educated you are about it, the better choices you can make, reguradless of how you approach birth and reguardless of the staff at the hospital.
For me, birthing my first in a US hospital and really having a desire to have an unmedicated birth, i feel it was imperative. Not so much for the actual labor part but just knowing how to decide if an intervention is necessary or not. So basically it gave me the opportunity to be a well informed consumer, which is very important for those wanting to go natural.
It also gave me and my dh some techniwues to cope. which was very useful.
The type of class you take will depend on your personal birth philosophy.
I def do NOT regret the $300 we dropped on our Bradley class (which btw, was comprehensive, it met once a week for 12 weeks, so far more informative than any hospital class can offer). We were dirt broke, recent college grads and recently married plus relocated, but i tell you what even though i dont have those professional maternity pictures done (ive got slews of bump pictures though!) im glad i spent it on the class instead bc i know i would not have gotten the birth i wanted (with a face up nonetheless) without learning what i did from the class. It was totally worth it and i believe it set the foundation for future births (Which it did).