I'd say the usnews rankings are useful as a very general way of measuring the education quality at different institutions. Any university in the top 100 should offer an excellent education. Tier 3 universities attract less gifted students, have dumbed down curricula, offer less undergrad research opportunities, attract lower quality faculty, etc. compared to a university in the top 100.
However, the rankings are meaningless when trying to compare schools in the same tier. For example, I know personally the difference between NCSU (ranked in the 80's) and UNC chapel hill (high 20's) in educational quality is minute, even though they are at different ends of the list.