I have read an awful lot of Piers Anthony Jacob - partly because his saleability meant I could find the books, largely because he wrote so many. In his SF he nearly always leaves holes big enough to drive a reasonable size space cruiser through; it seems that someone who is so careful with his historical research considers physics to be below consideration (examples? Take "Omnivore" where he asserts that the Manta's eyesight is sensitive enough to see molecules, so it doesn't require a sense of smell, or read "Ghost". I rest my case) and only character interactions (frequently not very believable either) are important. I know, this is what we're all being taught to believe now, but he's been doing it for decades.
He has his standard writing style, adequate if a bit dry, which he uses everywhere (after all, why change a winning formula), and remember; he was one of the first writing humorous fantasy. Previous to Xanth, fantasy tended to take itself very seriously, because that was what sold, and to a certain extent all the Pratchetts, Friesners, Gardners, Holts and so on are riding his bandwagon, even if they've added no few wheels and accoutrements themselves.
So, however negative this might seem, do try some – I'll join with the "Split Infinity" trilogy (but not the sequels) and add "Steppe" (which could have been an interesting series, save that the readers didn't follow.
His quantity is irrefutable, quality variable, but generally it's easy to get into the stories and there are always one or two details stimulating thought.
