I have not yet gone back to the beginning and watched the miniseries, but my understanding is that the miniseries is the only part that was NOT shot in high def, but all episodes thereafter were. I’ve only watched the extended, un-aired versions of A Disquiet Follows My Soul, Islanded in a Stream of Stars, and Daybreak, and the effects looked absolutely beautiful.
having a december birthday, i got the box set as a combo bday/xmas gift 2 days ago and we finally get to start our long awaited rewatch later today! !!!
plus it helps that my husband also wanted the box set so getting it for me was like a gift for him too. we didn’t own any of the series already.
we both have off for the rest of the year so we plan to watch as much of it as we want on our break 
yes the box is a stupid size/shape that probably won’t fit on our dvd shelf. and the way the discs are in sleeves like prev.poster said is also a bad design. The cylon toy in the top is also not worth discussing but i’m not into that stuff anyways. i’m just happy to have the whole series to rewatch whenever i want and am interested in whatever extra features there are (not sure what they are yet)