Probably cheap as heck to run as well. The second one I was in landed on a gravel runway and the strip could not have been more than 2000 feet long. When they took off, they only used 1/2 the runway, granted the plane was damn near empty and nothing but four people and fuel. Looking at the Wiki page, I was on the 40 seat variant, which fits for a lot of the operators up there; they buy used and surplus and run their operations as cheap as they can and not get fined.
If by "major" you mean United, Delta or American.
Man, fuck that plane. Been on exactly two of them. First one the pilot had a 'Nam flashback and nearly slammed us into a mountain making an "out of bounds" landing attempt. The landing was described by the luggage guy as "interesting, wasn't it?" Second one skidded down a gravel run way that may not have been legal but was described as "we do this fucking shit all the time and they ain't gone and fucking stopped us yet." Plane was at stall speed and probably the slowest landing I've ever been a part on. Probably a nice mid-range plane for rural Banjostan airports. But Alaska Pilots are all off their rockers. Some of the best (and worse) flying experiences you can ever have.
"Sporty" is a polite way to describe it. "Do whatever the fuck you want as long as nobody dies" is more apt. If you ever want to see what would happen to commercial aviation with no rules, oversight and regulation, go watch bush pilots operate. I've been on planes held together with tape, overloaded with cargo, with inebriated "walking drunk" pilots. Good Times.
Kenmore Air flies the float planes out of Seattle. They hit the islands of Puget Sound and British Columbia. There's Super-8 footage (that Kenmore Air does a good job of suppressing) from the '70s of that time they decided to see if they could put a float plane down on one of Mount Rainier's glaciers. Every now and then the news gets ahold of it and runs it and then KA basically purges it from the Internet.