Well for a word of advice, don't give up! We all started out just like you and worked are way up. All you have to do is to get used of sliding your pinky to orange and you'll be playing expert in no time!
Right, and I'd recommend you try hard bass before hard guitar as I find bass playing due to not having to worry about so many chords like with guitar playing adjusting to the orange button is easier learned with bass than guitar. So get into hard bass for a bit and then step up to hard guitar. Same process for expert imo. I remember well the days of Guitar Hero 2 where I felt like I would never get past medium on guitar but the above method is how I eventually adjusted.
This game isn't easy. I think they did a good job making the instruments in the game challenging for a band that favored the song and melody over flashy instrumentation. But really if you think about it this is the hardest rhythm game so far....because of the harmony vocals. Hitting triple fabs on expert consistently is a daunting task indeed!
For me this is has replaced Rock Band 2 as the goto party game because of the vocal harmonies. The solo vocalist on Rock Band pales in comparison now.