As a diehard 40k hobbyist I was really excited to explore this part of the universe. Rogue Trader did not disappoint in the least.
Incredibly voice acting and soundscaping. Right from the first five minutes I felt immersed in the world and soaked up every side conversation, every scrap of lore I could find. Characters are distinctly written and feel both human and inhuman at the same time; something critical to the 40k setting. My RT felt more like a flexible agent of himself rather than someone following an alignment rail or locked into dogma like a space marine, which was very refreshing.
Combat is crunchy and tactical - I recommend playing on daring to feel the weight of your decisions. Normal difficulty is a little on the easy side once you get the combat flow and spend some time reading your abilities and attributes. I played as a commissar and felt it was pretty accurate to lore. We even get the "Shoot your homies for a stat boost" ability. A+.
Spectacular storytelling experience, I can't wait for the DLC.
(Also props for fixing Marazhai's romance - hilariously, his relationship is dom/sub and the choices were either of those were flagged in reverse up until it was patched.)