Yeah, I like the fast-change aspect too. Also that the zombies were more concerned with biting to spread the "disease" and then moving on; rather than apparently not being very good at finishing their meals. (A zombie trope often glanced over.)
The only problem with the fast-change zombies is that it almost completely eliminates airplanes and mass transit serving as a successful disease vector. They kept the reference to "planes being a perfect method of spreading the virus" from the book, but in the book that was only the case because you might not be symptomatic for a few days (I don't recall the exact timeline) after being bitten or otherwise exposed to the zombie virus, in which case you would spread the disease to another continent without even knowing it just by taking an international flight.
The most dangerous viruses in terms of being able to threaten the world are not the ones that kill their host quickly, it's the one where you are a carrier for days or even weeks without being noticeably symptomatic, and that way you can spread the disease far and wide. Ebola for instance, as terrible as it is, is fairly restricted to isolated areas with poor medical care, because it shows symptoms so quickly and has such a high mortality rate that it makes it difficult for it to spread beyond a relatively small region.
They tried to explain it by having a zombie stowaway onboard a plane like a plague rat, but that only worked because for some reason that zombie was extremely smart and crawled into the cargo deck of the plane and then into the freight elevator where he waited patiently to surprise the flight attendant, and because since the airport was being overrun there were no guards around to protect the perimeter of the plane. Early on during the breakout of the virus that wouldn't have been the case, so I don't see how the zombies could possibly spread via airplanes so successfully.
In reality it would be fairly easy to create isolated safe zones on islands and so forth and not let any uninspected flights or ships come in.
Of course, as you guys mentioned, the slow-change zombies carry with them their own set of plausibility issues in terms of why they aren't easier to contain and defeat, so it's kind of a toss up there.
Objectively speaking was the fast moving zombies being able to detect sick humans any worse in terms of a plot than Khan's magic blood being able to bring Jim Kirk back from the dead and cure sick people?
Well, I commend you for moving beyond ST: Nemesis
as the only movie you ever compare any other movie's implausibilities to, but you know there are like, hundreds of thousands of other movies out there other than Star Trek films to serve as a basis for comparison, right? Branch out a bit.
People make a big deal out of the whole magic blood thing, but I don't find it all that bad. It's not even in the top twenty worst technobabble items in Trek. If you can genetically engineer someone to the degree they did with Khan, I don't think giving them some kind of self-repairing cells seem that far-fetched. Sort of like a biological equivalent of molecular scale nanites to repair damaged cells and internal organs. The Genesis Device in TWoK
was far more ridiculous if you want something to compare it to, though again, it's not like Star Trek is the only other movie series in the world.