A pretty lucky person out there is going to get one heck of a gift!
But, I agree you need to think this through and I don't think there can be a real "surprise". I don't think it's necessary to also pay dues for life. If you buy a house for someone, you don't also pay the maintenance and taxes for the years they live there! However, don't go into this without knowing if this is truly something this person wants and that they are capable of paying the on-going costs -- the yearly dues, the cost of travel to WDW, the cost of tickets, etc. etc.
You also have to be truly giving it as a gift -- they can do with it whatever they want.
Next question is whether you are buying it outright or will be financing through Disney. If you can buy it outright, I think the easiest thing would be to work with the lucky person and have them actually buy the DVC and you pay the bill. If you plan to finance, it gets trickier. However, I'm guessing the guides may be able to work with you on this. You may need to be "co-owners" at least until the bill is paid.