I really liked the characters in this and did not find them bland. I don't really see the criticism saying that Jyn is bland and has no way we can relate to her character either. At the very least her relationship with her father is one of the most visceral emotions that we can feel. Her seeing her father's hologram message, and then seeing her father die made me relate to her immensely. One of the best parts of the final battle on Scarif was when Jyn and Cassian are taking the elevator down, in complete silence, realizing their doom...all the way to when they eventually are engulfed in the explosion. You really feel for the characters in this; it was a true suicide mission and they went out guns blazing.
A New Hope doesn't NEED anything, but R1 definitely betters it. We did see the destruction the empire could cause in ANH, especially with the explosion of Alderaan. However at the time we barely knew what alderaan was, or who was really on that planet; yes for shock value it was crazy, but it was a fleeting moment/scene. Seeing what they do on a ground level, to individual people, is much more personal and much more clear - R1 made it evident. Seeing DV brutally rip apart those rebellion soldiers was just one example, as was the destruction of Jedha, as was storm troopers constantly bullying innocent people etc. They had a far reach throughout the galaxy and they terrorized people everywhere they went. R1 just adds a bit more depth.
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Also a side note, I didn't know Tarkin was CGI and didn't notice either; only until I read some stuff that I learned the actor isn't alive (which obviously makes total sense in hindsight haha).