This is the usual idle game with all the usual problems.
Unless you really like SF there's not much point playing this over any of the other near identical idle games.
The game is completely P2W If you're F2P you can get a few days or a week or two depending on how much you play, before you hit the paywalls. You will eventually just reach stages that are designed to be impossible to beat until you hit a certain power threshold. This could take days or weeks further into the game. The stage I'm at now I have been stuck at for almost a week and show no signs of being able to get past it.
The drop rates are awful for the most OP characters and you need multiples of them to power up. You also need gear that needs to be powered up but the game is extremely tight with giving you resources for that so you won't even be able to power up a set for one team. On top of that this is one of those games where you will need multiple teams to beat stages.
PvP is awful with bad matchmaking so you will constantly be matched with people with way higher power ratings meaning you know you've already lost before you even enter.
Once the "gameplay" runs out and you reach the eventual paywalls there's nothing to do but log on do dailies and log off again. There are some puzzle modes but they are more frustrating than fun.
Overall if you're not a whale that likes to compete with other whales to see who can waste the most money on a mobile game then I would steer clear of this one. If you're a big fan of SF and like idle games you may be able to get a few days of fun out of it before the game grinds to a halt.