...anyway, back on topic.
Overrated - dependent on individual likes/dislikes which rarely include any kind of objective analysis.
Underrated - ditto.
I don't get what the fuss is about The Beatles, however I see how influential and important they are yet none of their output speaks to me in any meaningful way, although I must admit I do like Being for the Benefit of Mr. Kite! But that's about it. I'd rather listen to one Sparks track than anything by the Beatles.
I'm not sure I really understand if the word overrated can be used as an objective term, I don't really like Bros but I think I understand their mass appeal, if there had been hundreds of screaming teenagers at a Public Image Ltd gig then I would have been confused. I suppose Adam and the Ants made a transition worth mentioning. I love the first A&TA album, Dirk Wears White Sox, it's one of my favourite albums but, gradually over the ensuing years their output became more accessible and gained broad appeal until they were huge and having number one hits. Despite me abandoning the Ant Ship around the release of Kings Of The Wild Frontier I still followed their progress with interest and still attended (albeit less frequently) their gigs right up until the Prince Charming era. I didn't personally like their direction but also I didn't start dissing them because they had become something different. I'm rambling, so much for on/off topic. Anyway...
Kraftwerk are (imho) geniuses of a scale larger than Miles Davis and Beethoven put together, utter nonsense of course but there it is nonetheless.