Some Trek Science is better than other Trek Science...it's dependent on how strong the story is on whether you'll start noticing the problems...for instance, Tuvix you'll let it slide, but Threshold will always be slammed and Parallax is borderline in my opinion.
Watching the Clock on the other hand - as I realise I have been posting in this thread without commenting on the book - is one of the best Trek Novels. Honestly, leaving aside practically everything else, taking two characters who appear for all of about 2 minutes (I'm sure Christopher will have watched the episode enough times to be able to say exactly how long!) and turning them into compelling characters is a real achievement in my opinion! I have Forgotten History on Pre-Order and I can't wait!