Why did you like it so much? I'm genuinely interested.
Hard to say exactly, part of it was my age when I first read it. It was one of the first hard science fiction universes I ever read, which made it automatically very different from most scifi I'd encountered at that point.
Ultimately, forcing characters to follow slower-than-light physics completely changes how the story can play out, and I'd never really thought how spending decades on trips between planets would preclude the formation of stellar empires or even a coherent civilization from playing out. People traveling to explore some dead planet would also by necessity have to colonize and rebuild civilization when they got there.
Though some of the science in the story is probably approaching fantasy, for the most part it remains grounded in reality and I really like the idea of exploring how advanced science applies to things like body modification and medical care, or space suits (specifically the suits in the first RS where they drop down from orbit in fusion-powered suits that make Ironman look amateur). One of my main issues with series like Star Trek is that the advanced science of the world never seems to apply to anything beyond space travel, people never use it to change their daily lives like happens in real life.
The initial premise of studying a dead alien civilization on a dead world and accidentally waking up a Lovecraftian species-destroying horror from the depths of space is just very fun. It's been used a few times now for various video games, but when I read RS it was a pretty new idea for a story setting.
And then there's the weird locations, especially Chasm City being a far-future transhuminist paradise turned rotten ruin, the Nostalgia For Infinity as a living ship ran from the brain of a frozen dying captain as it slowly rots as well, the Glitter Band rotating habitats made from discarded diamond hulls. It's a nice blending of various genres, bits of cyberpunk, horror, even some classic science fiction.
