Hi there
👋I have 44mm one, and so far no complaints apart from few things sometimes sleep tracking and fitness tracking is hit or miss and I'm still not convinced enough let's say go swimming with the watch on or jump in the shower with watch on it does say its water resistant but I'm still skeptical about that part as I take care of my devices and leave as far from water as possible
😁Sometimes find that inaccuracy in tracking is related due to watch being too tight or too lose on my wrist so it moves from perfect spot and stops properly tracking but I guess it's my fault, apart from that does everything you would want smart watch to do, beautiful screen, lots of features, great battery life if im wearing it it lasts around 1.5-2 days.
Now i have to agree with
@GusB as it's for 15 year old there's other cheaper alternatives like Fit3 whitch won't break a bank and does most of the things as watch 7, but if you're budget allows it then yes it's a perfect watch. Well at least from my personal experience.