It's one of the oldest running idol games and therefore lacks some of the flashy, colorful features that other rhythm games have these days, but it's definitely a classic that everyone should try out!
The graphics aren't anything out of the ordinary. The artstyle has been pretty consistent in recent years, but occasionally you'll get one of the older, wonky looking cards.
The gacha feature sounds horrible at first glance (only 1% for a UR) but the rates are raised every month in specific boxes, and they tend to give out SR, SSR and even UR tickets twice a year (either through lotteries or campaigns).
The music does have some variations of the usual genre, you'll hear J-Pop mostly, but the subunits also use influences from other genres like EDM, K-Pop, or western pop.
The story...eh, it's kinda just there for me? The anime is definitely worth watching if you want to get to know the characters better. Some in-game stories focus more on the members that didn't get too much attention in the anime though, which is great.
Overall, I think it's an absolutely lovely game that paved the way for many other popular idol/rhythm/gacha based games. It's a project that's brought me a lot of joy♥️