The thing is the Mini is easily topped up from USB, you could do it from a vehicle or power bank. so additional batteries are somewhat less important.
It's a nice entry level drone, and video and stills are surprisingly good - but more advanced users will hit the limits pretty soon with almost the only thing you can change being exposure compensation.
I've always had at least one spare battery but the majority of time I use it I do what I wanted on one then put it away.