The negative of these "deals" is that when you follow the long drawn out maintenance schedule by the manufacturer vs "real car guy" maintenance, you will be under-maintaining your vehicle. They aren't going to offer a short oci and you will be paying five times the cost for the dealer to do it. If you can not DIY, go to an indy and save at least half. Last time I did any sort of prepay was nearly 20 years ago when bimmer would only change the oil if the oil condition light went on or I got to 18k miles. Sure some people are idiotic enough to follow that type of schedule but I am not. That was when I learned that both CPO and prepaid maintenance are only there to take advantage of those that won't search out the proper answers for themselves. For 1400 bucks I could buy about ten oil, oil filter, and engine and cabin filter changes, with a round of brake fluid on top.
IMO the only positive is some convenience if they offer a loaner, and if you will turn the car back in before any warranty runs out. That way when the car needs an engine at year five, you won't be wondering if you should have done more oil changes. Lots of debate on OCI but the science speaks to long OCI being detrimental to todays engines and the oils lasting a much shorter time than advertised.