This place is good for what it is: Cheap fast food. I wouldn't consider it a great place to take a date or a fancy meal. It's in the style of an Americanized Korean place that also does Japanese food, which is not entirely uncommon in other cities. You aren't getting the most authentic Korean food, but it's not so bad.
I don't think the portions are so incredibly large compared to similar type places in California.
As far as Oakland eating options, this may be one of the best for quality, taste, value.