I have complained and been offered compension but have never taken them up on it. Our one and only cruise on HAL was brutal. Wrote them a scathing letter when we returned and they answered with all kinds of apologies and promises for upgrades, free dinners and VIP treatment on our next HAL cruise. There won't be a next HAL cruise.
More recently I contacted Princess and complained about the way they were handling their waitlists for cruises. They offered to bump me up the waitlist which I thought was ironic given the topic of my complaint ..we ended up not taking that cruise.