RPN (Reverse Polish Notation) is worth it, once you get the hang of it, much like riding a bicycle.
If you are anything like me, it will be a bit frustrating at first, but eventually you'll get over the learning curve and, free from the tyranny of parentheses, will be able to calculate stuff faster and more confidently than ever before. RPN means that you enter exactly what you mean into the machine. You know exactly what every button press is going to do, rather than keying the whole expression in at once, pressing "=", and hoping you got all your parentheses right.
That said, definitely try it out first to see if you like it, as I'm a bit biased (if you can't tell :) ). Give it up to a week of using nothing but RPN for your calculations for it to set in.
To try RPN out, just download Excalibur, an RPN desktop calculator. (Version 1.06 works better on Windows 8 compared to Version 2.00).
An intro to how to do RPN, and some of its merits.
Just a heads-up: the 50g has a bit of a learning curve, but this is mainly due to the fact that it just does things a bit differently coming from a TI.