It's a clunky front-end with a fragile back-end. While it superficially resembles Access if you squint your eyes, it can't provide more than a small fraction of its utility currently. Too many missing/broken bits.

I spent a couple decades as a power user of the MS Office suite and find that I can generally make Calc do what I need as a spreadsheet and even Writer as a word processor. However, pretty much every time I've tried to develop a solution in Base it turns into a fight and I end up throwing up my hands and going with a different database solution. Calc doesn't even work all that well with it... and it's one of the few applications that works with it at all.