Overall the experience will be worse. No doubt about that. Features like the Privacy Nutrition Scorecard (I can't remember what it's actually called) won't be nearly as powerful, for example, because other giant multi-national corporations will just create their own app stores to avoid playing by Apple's rules and "paying the Apple tax", which is something that they have to pay and end consumers don't. I.e. it's just a payment negotiation between big corporations.

It'll also lead to fragmentation and you'll have to manage 5-10 different "app stores" in order to use apps that you use day-to-day right now.

Overall it's just going to be a mess and really suck. Fortunately I don't use many apps so I don't see this affecting me personally other than occasional annoyance when I can't find something I may need in the future or having to help family members fix their phones now. For many though their experience using the iPhone will be degraded, particularly when it comes to software.