TL;DR Absolutely buy this if you're serious about learning to play the guitar.
Background: Been playing various six strings for more years than I can count. Bought RS2014 years ago out of curiosity so I'll recap my experience here.

The fun bits :D
1. Great for beginners, covers the necessary fundamentals of guitar playing via lessons (e.g. holding, picking, chords and MORE).
2. Session Mode - wasn't feeling it until I watched this tutorial to figure out the band setup.
3. Real Tone cable (4 years and counting) Mac compatibility with Amplitube and GarageBand.
4. The Riff Repeater, what a brilliant way to pour hours of practice into your jam-a-thon.
5. SP's Cherub Rock for its pounding intro and chord progressions so make this your first DLC purchase... you'll figure it out :)

The not so fun bits D:
1. Be prepared to spend a little more on your post-RS rig setup.
2. Input lag/crackling from the guitar to the desktop speaker which was later resolved by tweaking the rocksmith.ini file and changing the audio output source.
3. Note registration difficulties - there could be a song or two that suffer from this, but don't let that stop you from learning. update Resolved by using an external tuner. Keep in mind that string tension will alter as you tune from the low E to the high E string.