Game was a mixed bag plot wise, but was saved by its commitment to maintaining the integrity of the original cast. Zack was a great character, and you can see why Cloud idolized him; Sephiroth, as the OP pointed, got some time to demonstrate why he was so admired before he went insane; and Aerith's characterization remained true to VII, and allowed the audience to better understand her frame of mind and her attraction to Cloud.
On the other hand, most of the new characters ranged from inoffensive (Lazard, Angeal) to downright obnoxious (Gackt), with Cissnei being perhaps the sole exception. It's been a while, though, so I'm sure I'm forgetting other things I liked. I remember my impressions being pretty positive.
Seeing as how VIIR seems to more closely mean VII reboot than VII remake, I'm pretty certain we'll see several elements from Crisis Core integrated into this new series. That said, I'm not confident we'll see an exact remake or retelling of either this or DoC, since it seems SE is looking at the original compilation as something else these days.