I know a few AY Plat fellows and they seem to enjoy flying with AY. Preferential treament in general, skiing trips (Finnair hosts a major event in the spring), gifts (e.g. aluminium flying case, Suunto-watch or B&O phone), etc. Some of the advantages are not offered to foreign AY Plat's. If you travel a lot for business, either a lot of shorthaul trips or longhaul in business class, becoming AY Plat is not that difficult. I don't know if the rules have changed since but at one point you could become AY Plat with just domestic flights (HEL-OUL-HEL is a busy route).

As I'm personally not flying a lot for business, just vacations and short holidays, I'm now preferring BAEC as you can maintain BA Silver relatively easily and it does all I need -- business class check-in and occasional lounge access. The only drawback is that it was much easier to use AY miles than BA miles.