A law suit doesn't necessarily mean sueing. It can be a variety of things. The shareholder who filed the law suit is most likely looking for new management. However there is a small chance he will win. Either way this won't be good for Nokia.

Now it dents the companies image even further.
Later on if he wins and management does change along with their market plans, then they would've wasted alot of time and money. If he loses, it will still make people seem sceptical about the company.

This law suit although it has the right idea behind it, filing for a law suit in itself was a stupid idea for the shareholder. It's like saying, "Me and my girlfriend just bought a house, but I don't like how she moved stuff around and made it sound better than it would be. I know, i'll take her to court."

What he should've done is made his views clear at the next shareholders meeting (Or similar event). If not he should've sold his shares, you've got to know when to cut your losses. Keeping them is like digging a hole in the bottom of your boat so the water coming over the top can drain out.