I haven't used closeup filters in something like 35 years. Yes they work. Yes they will cause image quality loss. The more you stack, the more image loss. Only you will be able to determine if the loss is unacceptable.
When I did use them, I was happy with them. If you have AP auto exposure or match needle/led, I would reccomend extention tubes over closs up filters. And of course a macro lens is best, but costs a lot more than filters or extention tubes.
EDIT: If you know they are stackable, I guess you also know the order of stacking by powers affects the resolution. I think the higher powers go on the bottom, but I don't recall for sure. It's just been too long.
If I am wrong, someone will correct me.