Cons:
1) EVERYTHING that isn't human is definitely out to kill or eat you, possess your body, or devour your soul. Sometimes all of the above.
2) No central plumbing, so you'll be poopin' it old school
3) Bad place to have a curse at night
All joking aside, the fact is that if any of us every found ourselves in Castlevania made reality, the first thing we would think is "oh cool!", followed immediately after by the realization that you must GTFO post-haste, lest ye be converted into fertilizer.
If we had holy super powers, and ninja like reflexes and agility it might be a different story, but w/o said abilities each and every one of us would be food for some horrible creature within the hour. There's a reason that heroes like the Belmont clan are always shown vanquishing evil. Simply put, evil wants to kill and destroy you. And an evil like Dracula (who is always portrayed as being bent on world domination, but never makes it out of the throne room...poor guy) made reality, would be in need of being vanquished on the level of Hitler.
If you managed to escape from the Castlevania realm, the only game you'd ever want to see brought to life after that would be Harvest Moon or Animal Crossing.