I've had a pair for the last two years and so far really love them. I got them with winter camping in mind, but also use them for dog walking.
Pros: as mentioned above they are very warm and comfortable, but also very rather light weight. I feel like I am wearing a pair of slippers out into the cold. I also have a pair of lacrosse iceman pac boots that are warm, but super clunky to walk in. Have not used them since I got my Stegers. If the outers get wet, they do dry fairly easily if near a heat source. They are not waterproof, but can be made water resistant. Last January in the BW I was crossing a swampy area and punched through (and got out quickly) with each foot up to my knee, but got no water inside.
Cons: I'd be cautious about crossing a slushy lake where they would be in water for a long time, and I have been very careful to avoid oily spots in the garage or road given the warning Mocha provided on a past post. I'd also say the traction is not great given the crepe bottom, at least compared to a rigid bottom sole.
I really can't say much about durability yet, but have noticed some strain where one lace is attached. I'm not sure why Marsonite's could not be fixed though - seems like just stitching an inch of moose hide onto the back, but that's just my guess.
Like most gear nothing is perfect for all situations, but I've been very happy with my Stegers so far.