Buy Now or Wait for Revision B?

[Tugdual]

If you can afford the price and a hard lock during exams, buy.
Otherwise consider a robust and mature product.

In terms of features:
CAS, Geometry: you will find free CAS and Geometry applications on Android that are better than the Prime.

RPN Calculator: The Prime has a RPN "emulation" but it is in my opnion not a RPN calculator at the first place. A 15C or the 34S are much much better options for calculations.

To be fair the Prime improved with the latest firmware upgrade but there is still a lot that can be done to make it a good calculator. May be the 50g is a better option nowadays.