Even Real Rock Band cant play it.

[Spikes]

I run a recording studio and have played professionally for the last 17 years on both drums and guitar.  For an experiment I had a friend of mine come out and give it a shot.  He'd been playing Rock Band drums for a little over a year and never sat at a kit before in his life.  He wasn't going to win any music awards, but he was playing a consistent groove with decent feel within an hour of sitting down.  There were differences to work out, but he managed it and transitioned quite nicely.  Rock Band won't turn you into Neil Peart, but it definitely helped him learn the basics and coordination. 

The problem comes in transition from real life to Rock Band.  Your mind has to work a different way and I suck at it. 

I guess it was me going from real drums to fake drums that screwed me up. I'm sure if I wasn't used to the real set in any way I would do better with the RB ones...because I'd have nothing to go by...

[druski85]

There's absolutely no comparison. The game adds extra crap sometimes to make things harder, which gives people the idea that it's actually easier on a real guitar, but there's about 25x as many possible inputs on the guitar just based on strings and frets, not to mention that expression actually means something

Nailed it.  16 spaces on a fretboard vs 5 buttons, 6 (or 12) strings versus one tab thinger.  Volume differential, slides, hammerons that involve more than pressing a button, bar chords...the list goes on.  Two different beasts.  

As for the drum set, you have a better chance sure..but it won't make you a drummer as is noted.  If you have natural rhythm you probably aren't going to make a total clown of yourself on either.  (In my opinion, anyway)  

On the plus side, if you can rock vocals in game...you can rock vocals  I personally enjoy playing bass and vocals at the same time in Rock Band, as guitar riffs are usually more tricky to look at while looking up for lyrics.  

[Belial]

These instrument games require proficiency in the ganja, get high and try once.

[Enker]

The only instruments I can play on Rock Band are the bass and vocals, because those are the two things I can play in real life. Of course, the bass is much easier than the keytar part, and I had practice from when I found out about Frets On Fire (would you believe that I had no idea what Guitar Hero was before then?). Of course, being able to sing from high tenor with falsetto to lower baritone helps with the vocal parts.