Calling Rocksmith a game is a misnomer. It is simply a guitar teaching aid, that happens to play on consoles.
But that would belittle the true value of this title. I have had a guitar since I was 16, but due to lack of drive as a youth or perhaps the sheer dauntingness of trying to learn how to play it, it sat on my backburner of things-to-do for nearly a decade. In a month, Rocksmith helped me learn guitar skills to the point I can actually play fairly decently, to the point friends in social situations where there's an acoustic guitar I can go strum on comment on it.
First off, the way the game approaches teaching you is fairly intuitive. It starts off with "(Can't Get No) Satisfaction" by the Rolling Stones and you play literally all of two notes, occasionally, roughly every phrase. As you prove you can play those notes accurately and on time, it starts unlocking the whole phrase, note by note, until you are playing the song exactly.
Initially the game was a little on the grindy side as you would have to do this multiple times in order to level up a segment but they've since added a way to go into the training mode, set a song to whichever difficulty you feel you can play, and once you do it the song will then know you're at that level. Proof initial reviews are often misleading because quick system updates can solve an awful lot of problems.
Next, we have the mini-games, known as the GUITARcade. These feature various games which allow you to hone in specific guitar skills such as chords, playing specific notes without actually looking at your guitar, or more advance techniques like tremolos and harmonics. My favorite is "Dawn of the Chor-Dead" where you must play the chord shouted out to you by the game quickly enough your miniguns shoot the zombies trying to eat your brains. Attempting a high score in this mode has helped me substantially trying to switch between chords quickly, accurately, and all while learning the chords by name.
My personal favorite feature is one in which there is no actual feedback from the game itself, and that is the Amp mode. Once you do well enough on a song, you unlock the amp and pedal set-up used to make the song sound the way it does. After doing so, you can access them in Amp mode to make your own custom tones essentially turning your home entertainment set up into an amp.
The song list is pretty good overall. There's some indie stuff on there to go along with the big well-known bands, and there's enough diversity in each song to really highlight various aspects of guitar playing as opposed to simply being a "cool song." I can't stress that enough. Even if you do not like a song (I personally dislike the track "California Brain"), they all provide a balance and contrast to what you're doing in other songs. This might limit your enjoyment of the overall experience if you were to treat it like any old regular music game, but as it is really more of a teaching tool it works just fine.
Rocksmith suffers some minor technical flaws still. Trying to play on an HDTV in general tends to cause a delay in audio which even as minute as it might be, still is enough to damage your ability to play a song accurately. The recommended way to avoid this requires extra bucks spent on cables to plug directly into a sound system. If you're like me and just have the TV as your source of audio, you're out of luck. Also certain notes just do not like to register correctly at least on my guitar. I played it at a friend's house using his $1500 guitar and didn't suffer the same problems with notes registering; perhaps it has to do with the quality of the pickups on the guitar.
Visually the game is not overly appealing. You play in various brown venues with small crowds and unlock other brown venues with slightly larger crowds that are simply that small crowd layered multiple times. You also unlock new guitars, but the purpose of them in-game is meaningless because you don't ever actually see the guitar you select. Luckily that is not the draw of the game and doesn't detract from the experience.
Final verdict: I give it a 9 of 10 for what it is. Not a game, but a guitar teaching tool. While it has a few issues, they are easily overlooked as everything still works.