1. Make sure the Christmas puppy is a desired gift (including breed, size, color, and temperament).
2. Make sure that the person who you're getting the puppy for can afford to take care of puppy, and it does not just include food, but also toys, dishes, beds, collars, routine vet visits and possibility of emergency visits as well. Time also goes into this category, because some people work too much and cannot "afford" to give puppy enough time and attention, which more than likely will result in trouble behaviors.
3. Make sure person who you're getting the puppy for has suitable housing situation, especially if they do not live with you. Many rentals do not allow dogs or allow only certain breeds. Many houses do not have fenced back yard, and new owner will have to figure out how to maintain the puppy on the property. Puppies grow quickly, and can turn out to be a nuisance for the neighborhood.
4. Make sure the breeder will take puppy back if the whole surprise Christmas puppy idea will not go well. You may need to take puppy back, and it's much better to return him as a puppy to his breeder than not pay enough attention to puppy, and get rid of him later as adult dog sending him into sad life of being "re-homed" or be in a shelter.
5. Make sure you're giving Christmas puppy for the right reason: only to the person who truly wants a dog of this certain breed and can take care of them vs you ran out of ideas and just saw this cute puppy fairly cheap and it may work out as a Christmas gift.
Have a great Christmas season!