I love it and found it really addictive. However it is really difficult. Also depends if he likes flash graphics and a rapidly changing game. It's not the best looking and can get a bit samey.
However at that price may be worth trying if you don't mind the gamble.
I actually like where the gameplay is going from a conceptual standpoint... but the controls were very confusing. I'm told I may get into it if I try again... and that may be true.
I plan on giving it another shot when things slow down, but right now the Switch is getting nonstop fire right now
Buy Lego games..or mario kart Mario Odyssey..cars 3 ...all depends how good your 7 year old can play games ..switch has so many now..even the downloaded ones
The game is worth $10 its a massive grind fest its difficult for sure, it be to frustrating for a 7 year old though so not gor him but maybe for you at that price