It's good to be weary of gadgets that claims to make your life easier, especially around Christmas. They're often big, bulky, difficult to clean and only really serve a single purpose. There are, however, many new products hitting the market which are genuinely useful around the holiday season, as they save you more of that rare commodity - time. And they aren't season specific, they just happen to be most useful when you are most in need.
My top pick would be a steam oven. These have been around for a few years. The commercial ones have largely been streets ahead of the domestic ones, but now they've caught up. A good steam oven is like your KitchenAid. It's eye-wateringly expensive and you're likely to only use have the functions. They've gained a lot of popularity due to their ability to get pastries and cakes to rise with less fat, but let's be honest, also less taste. Forget the healthy aspect, it isn't what Christmas is all about. The steam function acts as a permanent baster , so you pop your turkey in and never need to open the door again. New models can link to the wifi so you can be swinging your heart out at church and quickly turn up the heat for that final hour's skin crisping. The extra moisture also makes cooking goose or duck a less challenging prospect, and if you splash out for a really good fillet of beef instead, then they sous vide so you can be guaranteed that melt-in-the-mouth texture.
My second pick would be a universal induction hob. These are exactly like normal induction hobs, but they don't have set heating points, they just heat any suitable pans placed anywhere on the surface. So you can have as many pans as you can fit, and keep moving them around so they all fit. A small screen will allow you to individually change the temperature of each one, fantastically useful for when you have 4 pots on the go and need to sneak the small pan of peas on somewhere for 5 minutes. Great for having everything warm whilst you're eating, ready for seconds...
My other suggestion would be the humble slow cooker. Once a symbol of 70s faddiness, they are now reborn as a shiny, easy-to-clean, wifi linked, indispensable gadget. They make fantastic sprouts, sauces, soups and dips, and all the hard work has been done the day before. Throughout the year they are great for producing home cooked meals on evenings when you are back late, and the long cooking time usually makes the cheaper cuts more feasible so they are great on the pocket.