It's not easy at all being a vampire in Skyrim and I learned that the hard way: by becoming and by living as one for a while before being forced to load a previous save and lose about 4 hours of play time.It all happened because I got bit, as with all great vampire narratives, and, in the heat of battle, I forgot about the message that talked about a new disease and so I never used the Cure Disease potion that could have saved me a lot of trouble.
I was deeply engrossed in a quest so I forgot to visit temples and pledge allegiance to a new god, which eliminates all negative effects, and I rarely bother to check the Active Effects section of my character tab (the annoying interface might be partly to blame here).
I noticed that something was not right when my blood literally started to boil when I got out in the sun but the effects were not too bad for my character and I was very set on finishing my current quest than on currying whatever disease was affecting me.
Only later I paused to favorite a new Shout I discovered and looked at the Active Effects to learn that I was close to becoming a full blooded vampire, with some nighty bonuses to sneaking and night attacks and vulnerabilities to light.
I was still not troubled and a little curious to see how a vampire plays in The Elder Scrolls V: Skyrim.
I decided that a second playthrough would be a better time to experiment and started the quest to cure my vampirism but, after a rather long fast travel, I was shocked to see everyone in a town attacking me viciously.
Regardless of the town I was shunned and attacked and it became rather clear that I need to go back to a time just after being infected in order to cure myself and prevent my Skyrim game from changing completely and so I lost about 4 hours of real world time because I forgot to do something as simple as checking on my status effects.
I then found out that vampirism can be brought back to stage one by feeding and that as long as the player micro-manages well it's perfectly possible to play Skyrim for long periods of time without being attacked as a vampire.