Ive always viewed Koontz work as "Quantity" over "Quality"...Ive read some of his books and most that I read were duds (IMHO) with weak plots, non-believable characters (and especially character traits), and juvenile sequences. There were many that started off great with so much potential but took a turn for the worse ( for example "TickTock")..........
....However, this doesnt mean that I disliked all his work: The "Odd Thomas" Series was fabulous - great plots ( at times a bit 'out there' but Ill grant his Creative Licence), great characters, and decent storytelling....Another book, "Phantoms", was also very good and I was surprised how much SK's book written a decade later, "Desperation", was similar to it in various ways
I'd rather have Koontz write less books but more "Odd Thomases"