Recently I've read two books in series started by an author now dead. One lived up to my expectations while the other I doubt I'll bother to include in the canon of that series.
First is And Another Thing by Eoin Colfer. This is part six in Douglas Adams' Hitchhiker's Guide to the Galaxy trilogy. I had not previously read any of Colfer's work, but have heard good things about the Artemis Fowl series, so I didn't go in entirely pessimistic, but I can't say I was expecting greatness. Which is just as well, because Adams set a high bar, and unfortunately Colfer didn't reach the bar. The introduction was promising, but Colfer couldn't work Adams' style, and the voice of the piece felt off. The guide entries in particular did not work as well they did for Douglas Adams. Overall I though it was a story that might work OK, but didn't fit the characters and the world that it was grafted onto.
The second book I found did a much better job of things. The Gathering Storm by Robert Jordan and Brian Sanderson (Sanderson's name is about a quarter the size of Jordan's on the cover, which is not to unfair since Jordan did manage to write the previous eleven books on his own before passing). Sanderson's style, while distinct from Jordan's is a good fit and does shore up some of the weaknesses that Jordan had, the big one being the at times horrendously slow pacing. In The Gathering Storm things are always moving along, and for the first time in many years, you begin to feel like you may actually see the end of the road. Numerous plot threads were tied up in this volume, some of which have been dangling since the early books. All in all it is a much more satisfying read than And Another Thing.
I don't know if there will be another Hitchhiker's sequel (I'm not sure I'd read it if there was), but there are two more Wheel of Time books to go (I've heard rumours of some prequels as well, but nothing is happening there until after the series is finished) and I will definitely be reading them (I started reading the series a decade ago, a decade after the first book was published) as I do want to see the end. I just hope Brian Sanderson can keep doing such a good job.