The overall gameplay is fairly simple. Although I play other rhythm games easy is not easy.
It took me a while to figure out how to progress and unlock more songs. The game gives players 3 keys which can be used to unlock songs, my suggestion is Umaku Ienai and Fiesta Fiesta since those helped me unlock more.
Songs are unlocked based on score and how well you do in the lives. Good cards (aka SRs and LEs) are a MUST to get a score higher than an B or A (which is the requirements for unlocking more songs). I don't know if it was programmed that way, but I was able to do free 10 rolls in the gacha a few times to get cards which significantly boosted my score. As a reference, wirh starting cards with a perfect score on hard I was about a lower B range. Now I'm above a B, sometimes get a SS.
At first, I wasn't a fan of this game, but it has grown on me and I can see me playing it more often. But be advised the loading times can be quite long and you do have to play a single song at least 3 times to unlock the other modes of play (extreme/extra). But if you a Hello Project fan and got time to play, I say try it out!