It highly depends on what is you want to use Japanese for.
I am not good at remembering grammar, but need it for obvious reasons, especially now that I signed up for JLPT. I tried different methods, bunpro was the most suitable for me.
Bunpro is good to force grammar points into your brain, if that is what you need. It is what I need.
Especially, when I type the third conjugation version of the same grammar point and get the message of “can you use a more casual form” or something along those lines, and I just want to chuck my phone out of the window and stomp around like a Gondzilla, that gives a lasting impression on my brain. Unfortunately that happens quite a few times, so many grammar points are associated with full rage in my brain…
Edit: I do not like the vocab feature though, anki somehow is more suitable for me when it comes to vocab.
Edit2: bunpro has a lot of features, grammar, vocab, kanji, reading materials, jlpt tests, so it is worth the money in my opinion and from what I have seen over the years, it is one of the most wholesome apps out there when it comes to Japanese language learning apps.