When at 2000 RPM, the fans are not noisy at all. It`s very silent, actually. Usually, the fans get this RPM when using safari, pages, itunes and similar applications that don`t use much processing power.
When the the RPM doubles and goes to 4000 RPM, I can hear the fans but nothing that bothers me. I get this when watching high definition videos or play games on my macbook.
I never had a laptop before, so I can`t really compare to anything, but I can say that overall it`s a very quiet computer and I like it a lot