I was there for a month around Lahti in July and loved Finland and the Finns (well OK one in particular). We didn't do any serious wilderness trekking, just camped on the lake, fished, canoed etc. but I everything had that clean, clear feeling to it. And I guess because summer is short the plant growth is amazing, everything still fresh and green, not that dull colour we can get as things age. The weather was great often up in the 30's so being out on the water was a must and swimming was fantastic, and sitting there at 3 or 4 am in daylight!! Well it confused the hell out of my body clock, but I wouldn't have missed it for the world.
Loads of people spoke English and were shyly happy to do so, I tried to learn as many useful Finnish phrases as possible just so I didn't come over as cocky English person expecting everyone to understand, but they didn't really stick.
As for the mossies, yes they're huge, but they're lumbering slow moving things and you can feel them settle on you before they bite so I rarely got bitten (I seemed to eat quite a few though as they had a habit of landing on my food just as it went into my mouth).
I picked up a bit of kit while I was there too, including a great pair of Nokia's (wellies), and some fishing gear. Beer's bloody expensive though.
Next time it'll be winter just to experience the same landscape with snow, and driving out to her island summerhouse over the ice instead of canoeing across.