Re-recorded dialogue surely heralds a few changes in the voice cast, especially as Jack Ritschel (Zeratul, Edmund Duke) has since passed away. Some will be brought in line with the SC2 cast, I would expect.
Some of the remastered art (like the Hive) does look a little shiny, and a bit of a departure from the desaturated look that games like Factorio have managed to capture just fine in their 3D renders.
imagine if they replaced glynnis talken campbell (bw kerrigan) with sc2 kerrigan (tricia helfer)