If your objective is just to have fun, then it does work fine for beginner. As a beginner guitar player myself, I found the starting skill levels on Rocksmith 2014 to be really easy. It does jump up quite quickly in skill level, though, if you don't know what you are doing. Admittedly, I just got the game myself and haven't spent much time with it.
If your objective is to teach yourself the guitar (without lessons), and you want a computer aid, then one of those online lesson sites is a better bet, in my opinion, as you will get more focus on technique and a bit of music theory (though I haven't seen too much of the latter). However, there are some crap sites out there. I've tried Jamplay.com and thought it was pretty decent for what it is. You can usually find the first month for half price ($10), so wait for a month you're not very busy and give it a try.
From my limited experience as a beginner, it seems that Rocksmith, while playable by a complete beginner, is probably better enjoyed after you've learned some basic technique (ie, fingering of a few basic chords/progressions, and a scale or two) and a bit of muscle memory. Though, technically, you can learn much of this with the lessons in Rocksmith, I personally found it easier to learn from an actual instructor video (ie, Jamplay) and with a bit of practice on my own.