I'll try to keep spoiling to the minimum. TL;DR: This is the life story of a future star singer. Tamura Eriko is not your typical usual student as her parents are rich and famous people. Her life could be a sugar bowl but not everything is happy in the real life. Life of a starting singer of 80s has its advantages and drawbacks. Unlike most of recent romance comedies this anime has surprisingly strong and consistent plot. Yes, fillers are present but not too often. Predictability of the story development is about 40-60% (vs 95% in modern anime) and this is why I liked it. Characters arewell written. Every single one, even minor personage has a believable character without much overacting (like in modern shows).
No grotesque tsunderes, no stupid average school boys, no stereotypes. Awesome!

Eriko herself is too naive and sweet sometimes, but she's only 14 (in the 1989) so it isn't much of an eyesore (unlike the "TRASHY MAN") or Mary Sue. She has bright personality, hardly ever gets angry, excels at every activity and always puts the needs of others before herself, also can be described as a hard worker on the whole.

The music is nice and not easy forgettable. I really liked "Serious" song (真剣).
Soundtrack is good (like most anime soundtracks from the end of 80s).

Designs were pleasing to my eye. Sure, secondary characters sometimes have derpy faces, coloring is off, backgrounds are mostly simple and Eririn's expressions from 48 episode are creepy.
But! Those faces are not copypasted plastic mannequins (like in Sailor Moon Crystal).

Cons: show is repetitive (songs, some scenes), sometimes prolonged where it not supposed to.

Overall, I did enjoy my time with Idol Densetsu Eriko, and I'm definitely not a romance fan. In the end, there was plenty of room for improvement, but it was quite a charming show. I'll give it a 7+.