What are the original DOS games like and how do they compare to the remakes?
I don't know about the remakes but the originals are kind of complicated.
You have dozens of skills and spells that are completely useless or next to useless and the game system is hard to understand if you aren't familiar with the tabletalk rules and even then there are a lot of things that are handled differently.
The plot gets progressively worse and by 3 it stops making sense.
Encounters and events are presented as text so the 3D view feels lifeless, especially in 3 with its full 3D graphics.