I bought Rocksmith this past December for PC on Steam; including the bass DLC and of course the proprietary 1/4" TS to USB cable. 5 months later, I'd have to say I'm throughly pleased.
I think Rocksmith is excellent for teaching beginners and intermediate players popular songs. Someone who is a complete NOOB can play songs fairly competently within a few months.
It's a little pricey, especially for the DLCs, but it beats the pants off of all the crappy tabs floating around that beginners often rely on to learn songs.
However, I do have a few gripes with Rocksmith as a learning tool.
1.) Rocksmith doesn't teach music theory. It shows you how songs go and you as the player are supposed to mimic the sound, but it doesn't teach WHY. Things like key signatures, time signatures, dominants, chord progressions, key changes, modulations, A-B sections (or what a verse, chorus, bridge is) are completely untouched, leaving beginners and intermediate players devoid of knowledge that helps them become better musicians.
2.) Primarily as a bass player, the chords are noticibly absent. Since I play more jazz, funk, neo-soul sort of stuff, I'm used to reading "lead sheets", basically sheet music with the melody but the chord symbols are above the staff. Rocksmith has no such way of indicating harmony. All I see is a flurry of colored squares, and I'm not thinking "play this riff on the 8th fret of the yellow (A) string"; I'm thinking "Fm7 arpeggio". But a beginner wouldn't know to think like that. This is especially bad on songs that shift keys or have lots of chords. It would be nice to see the chords floating above the track so we know what the overall harmony is.
I'm not dogging Rocksmith, I think it is a genuinely valuable learning tool, but I think it could be improved in the aforementioned areas.
I think for more intermediate/advanced musicians, investing in the Transcribe software (which is excellently designed) might be a better investment, but it certainly isn't as fun as playing Rocksmith!