I remember when The Modern Age EP came out it went through the college town I lived in like wildfire. By the time this album was released we were in a fever pitch of excitement, and, when they finally came through on tour, it seemed like the whole town had a collective orgasm.
I think Julian Casablancas described it really well when he said they sound like a band from the past who took a time machine to the future to make a record. More specifically they sound like a New Wave Velvet Underground to me. Similar to many other bands of the era (White Stripes, et al.), they weren't doing anything radically new per se, just putting the pieces together in a new and novel order. Like an irresistible sort of processed food that has refined their formula to become completely addictive.
The hype surrounding them was enormous. So big that it was inevitably unsustainable. After they came through on tour and we all had our collective orgasm on that one night stand, it never felt quite the same again. At the time I was convinced the album title was a reference specifically to the impossible-to-live-up-to hype that surrounded them and I thought it was quite a clever way to address it. Is This It? Indeed it really was that simple. But man they really caught lightning in a bottle here and I was deliriously giddy being swept up in Strokes mania.