I could hardly care less for a buggy and intrusive application that is only a glorified wrapper for the corporate website. Last I tried, the American application was a bad joke: check-in always failed and locked me out; and the built-in sudoku were not always solvable!
Finnair has a mobile version of the site, which works just fine for typical mobile activity such as online check-in. I'd rather they don't waste my Finnish taxpayers money writing a pair of stupid iOS and Android applications,