I've got the original, and to be honest it was a massive disappointment.
If you can already play the guitar to a level where you can strum pretty much anything if you're given the chords, then this will be hugely frustrating as there's no easy way of picking a section and setting the difficulty and tempo. It's all done on how the game thinks you're doing and whether it thinks you've hit the notes or not. I'd say it's about 95% accurate, but sometimes I knew I'd nailed a section but it would say no! or I'd fluff a note and it would let me past.
If, and it's a big if, RS14 now has that option, then it'd be worth a buy. If not, I'd leave it.
And all that said, if you've ever picked up a guitar in your life I reckon it's an excellent teacher for the absolute beginner, as it explains everything clearly and builds you up slowly. I'm no maestro on the axe, but even I found it too basic for my needs.