I finished reading Sundiver last week... I’d put it in the ‘just ok’ category. I wasn’t bored while reading it, but I never felt invested in the characters or cared much about what they were doing. The main plot revolves around humans discovering sentient beings that live in the photosphere of the sun. It seems, however, that everyone on the ship (including a few aliens) has different political motivations for being there. Meh...
However, the story is set in an intriguing universe which gives me hope for the remaining books of the trilogy. The main catch of this universe: every sentient race was “uplifted” to sentience (through genetic manipulation and mentoring) by other sentient beings. Every race, that is, except human... It’s unclear whether some being started us off and then abandoned us halfway through the uplift process or whether we somehow evolved naturally to sentience (which is unheard of in the billions of years of universal history).
Anyway, this was Brin’s first book, so I’ll cut him some slack on the plot. I would be reading the 2nd book now (Startide Rising) if I weren’t a second class citizen of the Clackamas County Library system. Since I do not have an Oregon driver’s license, I am only eligible for a probationary library card which means, among other things, I can’t place holds... and the nearest available copy is in Wilsonville! So, I picked up Red Mars (which was available at Ledding) and have begun reading it. I’m about a quarter of the way into it, and it’s really good! More about it once I’ve finished it.
I warned you that Sundiver was the weakest of the series. Startide Rising is much better, especially if, as I do, you enjoy the way Brin brings other species to life. Nothing I've ever read has more ALIEN aliens (and I'm categorizing dolphins as aliens here).