First, let me preface this review by saying that I love rock music, especially during the pyschedelic era. That said, the EMP Museum is like a Disneyland for me.
They have extensive collections devoted to Jimi Hendrix and currently, Bob Dylan, including handwritten lyrics, photos, instruments and other memorabilia. There are listening stations and videos playing everywhere, detailing the lives of these artists into minutia.
There is also a circular room that has all manner of guitars, ranging from the earliest to most recent versions. Unfortunately, visitors can only look but not touch.
Other exhibits include blues, Motown, and hip-hop. I found these less interesting, but most likely due to my personal taste.
Actually, the most disappointing area was called the "Northwest Passage," a section that supposedly celebrates homegrown musicians from this part of the country. Many of the groups represented are obscure, one-or-two-hit-wonders. But what I, and I'd imagine most other visitors, sought here was an inside look into the (in)famous Seattle "grunge" movement. However, all I found was a small area that has a few early album covers, random instruments, pop music magazines, etc. Evidence of major bands like Pearl Jam, Nirvana, Alice in Chains, Soundgarden and Mudhoney are barely even apparent.
But the museum has other highlights. There is much to interact with here, including guitars, keyboards, basses, drums, scratching turntables, all including on-screen tutorials if desired. You can use a soundproof room or even have an onstage experience.
Overall, if you are not into rock music, this is probably not the place for you. But if you are, I'd recommend it wholeheartedly as a chance to experience and be inspired by those early "rock-gods" who made it look so cool and easy at the same time.