I personally think TOS-R "The Doomsday Machine" is one of the worst of the TOS-R episodes. In my opinion at least the original effects looked better than the cartoons that replaced them. The texture on the doomsday machine itself was just pathetic. Don't even get me started on the interior of the machine or the super cartoon looking force beam that it emitted. It really renders one of my favorite TOS episodes unwatchable for me. To me the remastered effects were nothing more than a gimmick but I'm glad to hear that some like them.
That episode is a great example of what I said some posts back re CGI effects made by people who don't understand how light works on film. The Planet Killer's original beam flashes through a whole series of colors which gives it this hot, energetic pulse which is completely absent in the remastered version effects. Don't even get me started on the pathetic barfing up blueberry juice explosion at the end.
Also, the animators add pointless excess motion which negatively impacts the drama of certain scenes. The animation of the Constellation heading into the Planet Killer's maw is needlessly hyperactive. The ship slaloming around undermines the ticking clock. It's a death march, not a luge ride.