The Mercenary Koch: The image is a little soft, yes, and when you watch it on a gigantic screen (larger than, let's say, 32") this might be a problem
I guess it's the problem of the original source; the French disc seems to have the same problems, according to reactions (and screenshots) on the French western forum.
About the sound: just read an article about this 5.1 thing; more and more people return to stereo, 5.1 was a hype and it could be over rather soon. Theaters aren't good places for 5.1 mixes (you have to be in the center of the speakers) and even in your home it might be difficult to find the right place to sit. There are also very little real 5.1 mixes, most mixes called 5.1 are in fact 3.1, with some surround effects added to give you the impression of 5.1. Another problem of those 5.1 mixes is that they tend to make dialogue hard to understand. People want clear effects, so ambient sound is often preferred over dialogue.
And then there's the problem with 5.1 sets. If you want to spend, let's say, 600 € for a set, you can buy a decent stero set (300 € for the receiver, 300 € for the two boxes), if you spend the same amount on a 5.1 set, you may end up with very average stuff. A good subwoofer alone, costs some 150 €, which leaves only 450 € for the rest of the set. Count at least 200 € for the receiver. This leaves only 150 € for 5 speakers. This is impossible, so most people fall back to inferior receivers and boxes, or buy an all-in-one set, which usually are of modest quality, to say the least
I have a surround set, decent quality, no more, it does the job, only ... most of the time it doesn't have a job. I have a stereo set too, which is of superior quality: a much stronger receiver, much better boxes. Okay, it's not 5.1, but the sound is more powerful, brighter and clearer.