I really think if you want to learn the guitar you need to rely on actual proper practice on top of Rocksmith.
If you can't hit a note cleanly, why not unplug from the game and start on the open low E string? Use down strokes and play them until you can consistently nail them cleanly, then do the same with upstrokes. When you're comfortable doing that, start alternate picking. Then move to the A string and repeat. Or even start picking and fretting notes on E, then just move up the string chromatically. Say the notes out loud as you go, as you're not just practising physically moving around, but you're learning what notes your hitting and starting to train your ear. That's a tonne of stuff that you really have to nail down and you don't need to be on Rocksmith for it. Baby steps and all that.
Take time with a book and don't even touch the guitar. Read up about basic theory like how chord progressions work, modes of the major scale, how chords are constructed, learn note positions on the fret board etc.
Depending on how serious and rigorous you want to be in your practice, this seemingly simple stuff will take you weeks, if not months to pin down, and you're as well to lay down a solid foundation. It won't happen instantly, but you will eventually have an 'eureka!' moment.
Anyway, good luck with it, whatever you decide to do
Edit - Also, what Duffman says
Edited by FuzzyDuck at 14:18:14 08-10-2012