It has a slow start, but once you get further in it starts to get very addicting and fun.
The pool expansion upgrades feels like it need a limit though since there is an actual limit to how many balls there are. From my count using the upgrade itself and an empty bingo roller thing (sorry I don't know the correct term for it), there are 147 balls in it and, as far as I know, there isn't a way to increase or decrease it, which mean pass that point there is no use upgrading the pool size, yet you can still upgrade them... a lot
the auto spin looks like it should also has a limit but... the upgrade seem to still have an impact despite the RPM not increasing pass 57.3, so I think it's fine.
also for other people who plan to play this and starting to grind for prestige, I think it's better to not upgrade the board size too much too quickly. while larger board gives a ton of payout if you get a full board, getting all the card first is an absolute grindfest, which is worse when the board is exceedingly huge.