Come for the nostalgia, but it has one of the most unforgiving gameplay mechanisms I've seen even for a game of this type. This game absolutely deserves one star, but just because I'm giving it one star doesn't mean this app fans shouldn't try this game. It's free, and you get the voices. But as a game, it is just anti-fun. There's a drop rate based on RNG, so you can't play according to your schedule because something may not drop. You can't plan out how to get drops. Right now, there is the October 2017 Hell on Earth event, and there are space missions where you have to sit there and grind about 10 battles. In each battle, you make your characters fight monsters at 1 damage per hit for an over 200hp enemy, and it takes 8-18 minutes to complete a battle. And you just have to be there just to make sure your phone doesn't turn off so the battle is successful. There's no gameplay, you just have to be awake, and bored. What's worse is that if you spend money on premium currency, you can supposedly bypass some of this hassle by getting more bombs that can kill these enemies, but even then, the management of the bombs is so hard, due to the learning curve and a bomb capacity, that even the paying customers probably have a difficult time progressing on this event.
So, this is just a game that isn't fun, and paying money isn't going to make the game more fun. But, the nicest thing is trying to get some of favorite characters, if you are ever so lucky!