In my opinion it likes being overexposed, I like how it renders colours more pastel that way. I shoot it at EI200 and sometimes EI100.
A lot of the photos on Flickr taken by Japanese photographers are even shot at EI50, 25 or even more. The colours will go very pastel then, which I like.
You should shoot a test roll at different ISOs and see what you like the best. If you want very saturated Ektar like colours or even portra 400, this isn't the film you will like.