I visited the Finnair Premium Lounge in Helsinki in October 2016. Compared to the Business Lounge next door, the Premium Lounge is a smaller, more exclusive, lounge, only open to Finnair's premium frequent flyers and Oneworld Emerald. At off-peak hours, they sometimes open entry to Oneworld Sapphire members (Who would otherwise have to use the adjoining Business Lounge.)
Coverage of the lounge in a TR here.
Coverage of the lounge in a TR here.