If I wanted a Giant Hairy Dog, that's what I'd get. The training director and one of the other trainers at my obedience club have them, so I've met.... four? Plus we have two at work. They're all really nice. Big, lumbering, laid-back. Ira's old guy did obedience, rally, and is actually titled in flyball.
IME, the same health issues as other giant breeds-- I'd definitely want to see hip and elbow certifications done if I were buying one. Right now they're not very common, so they are better bred and healthier than a lot of the Giant breeds that I see (Berners for example). I hope they stay unpopular because I'd hate to see them ruined.