In our experience, some are more comfortable than others. We once had an AWFUL one at OKW and after we called Maintenance/Housekeeping, they replaced the mattress pretty quickly for us. Since OKW is an older resort, it was reasonable to think the mattress had seen better days....and it had! The BWV is not a new resort either, although renovations may have been recent. It does not hurt to ask.
So don't suffer in silence!