Eh, why?
Disadvantages in comparison with today:
Almost non-existant levels of medicine and medical knowledge. You could die from a relatively minor cut if you were unlucky.
Plague, plague and more plague. The Great Death of 1347-50 is the only really famous medieval plague, but plagues of varying severity and scope were commonplace. There were others that killed as much as 10% of the population. Try to imagine a plague killing several million people in a few months in the UK today. You almost certainly can't. If you lived in medieval times, you wouldn't have to imagine it.
No plumbing. No sewerage. No food preservation. No central heating.
Fancy having 5 children and watching 2 of them die before adulthood? That was normal - preadult mortality was about 40%.
War and conscription for men. Maternal mortality for women. Whatever your sex, chances are that one would impact on you directly and the other indirectly.
Vast class differences and much less social mobility, especially in early and mid medieval times. Even after the sizeable increase in the number of rich commoners in later medieval times, the difference was still huge and the chance of rising was slim. You would very likely be a peasant all your life. Which would almost certainly be short due to a combination of hard work, an uncertain supply of food usually of poor quality and a total lack of healthcare other than the herbal remedies of the local wise(wo)man if you were lucky. Don't bet on living past 40. Actually, don't bet on living to 1. A large minority of people didn't make it that far. Enjoy your one-room home made of thin branches and mud while you can.
Maybe you would be a wealthy merchant or nobleman, but you'd still have a standard of living and a life expectancy below that of a minimum wage worker today, i.e. a modern peasant, and you could still easily catch a plague and die.
Advantages in comparison with today:
?
Medieval history is fascinating and I'd like to visit, but I sure as hell wouldn't want to live in it.