It means you can expect 3.41% over the course of the year. This is usually distributed quarterly.
As to whether it's a good long term investment, that's going to be a matter of some opinion. It should be relatively low risk as McDonald's certainly isn't going anywhere. It will also be relatively low growth as McDonalds is, well, everywhere. I would anticipate growth to be slow but steady as McDonald's goes into emerging markets, and the worldwide obesity problem continues to get worse. I also happen to think that McDonald's is large and clever enough to adapt to trends.
In other words, don't expect to do a whole lot better than the market as a whole, but don't expect to be out your money entirely either.