It's not too bad if you use the firebase store. But yeah using the firebase realtime db for anything that requires relationships/indexing can be kinda cumbersome.
I've built a prototype on top of it and it's fairly rudimentary but you can make it work. My biggest concern is that there are no case studies I can find of people using it past the prototype stage and how the pricing/scalability works out at that point.
We've spent a lot of time working around the limitations of FireStore, but it does work reliably. Pricing is VERY hard to extrapolate from early use; all it takes is one feature request and your assumptions are blown.
Love to hear from anyone who has gone beyond the prototype phase.
I've built a prototype on top of it and it's fairly rudimentary but you can make it work. My biggest concern is that there are no case studies I can find of people using it past the prototype stage and how the pricing/scalability works out at that point.