I'll start with the DS9 book The Long Night, which I read last weekend when I should've been doing homework. The basic idea was a good one: the discovery of a long-lost fabled ship and the complications it adds to the present political situation. Sisko's fascination with this ship was believable, considering the Bajoran solar ship and all (though that episode may have aired after this book came out). Jadzia's was also believable, although I thought it would've been better off attributed to Jadzia herself, or another earlier host, as opposed to Curzon. The writing kept in character; Nog had a particularly good quip, "I thought jokes were supposed to be funny."
My issue was that too many doctors just happened to have extensive experience in cyrogenics, which was awfully handy and not remotely believable. The two doctors that just happened to be there happened to have useful backgrounds, which was overkill since Bashir filled his history of medicine requirement by studying cyrogenics. Never mind suspension of disbelief - you'd have to throw it out the window. The medical part of the novel near the end was weak and sullied the book. This is regrettable because it was otherwise good.
SPOILER!!!:
A quick miracle is cooked up and not only is the guy who's been in cyrogenic suspension for 800 years revived when it was nearly impossible 100 pages before, he recovers in astonishing time with no apparent ill effects from eight hundred years of cellular degeneration. This was a big deal until the end when Presto! he's cured.
Final analysis: if you see a cheap copy at a yard sale or book sale, pick it up for a boring day. Don't go out of your way to acquire and read this one, though.