For anyone who's a fan, this is a must-buy. For anyone who isn't a fan, you'll enjoy it anyway as it doesn't hinge on former knowledge and is genuinely a good story, exploring the different forms of friendship, love and loss, and the way we express them.
It's well-written, drawing you almost immediately into the feel of the series with several plots which weave in and around each other in a very satisfying way. The understated characterisation of Jeffery Sinclair, Catherine Sakai (both quietly determined people, and the balanced partnership of a couple is rarely seen and very nice to see) and Marcus Cole (sorely missed, and in this incarnation still wracked by helpless fury at himself and fate) is pretty much spot on what we saw in the series. This look at a part of their story we only heard through hearsay before just makes us love the people that much more.
The one flaw which made me drop it to 4 stars, was the fact that the timeline doesn't quite agree with that implied by some comments in the TV series from the characters involved.
Having said that, enjoy it, it's a good book.