should i buy nami

Yes.

Yes she is very good, 2 of her abilities are very simple to use. However her skill cap is quite high.

Yeah she's one of the more balanced supports.

nami is lit, she's always been good

She is a good support. However, she has a steep learning curve, so you may have difficulty playing her effectively in the beginning. She requires good timing to use her. I recommend waiting for when she is free in the weekly rotation and try her out.