Now the sun is out and we all know the sun hurts vampires...
Only when the vampire hasn't fed recently. As long as you stay at 25% you're fine.
Even 50% is manageable if you don't fast travel and keep healing yourself on the way to shelter -- and even then, it's most important when the sun's out, because cloud cover will slightly reduce the amount of sun damage received. Just need to use some common sense.
Being a vampire doesn't mean automatic death from sunlight. It's only at 75% and 100% when sunlight becomes dangerous.
I've had a Khajiit who played a vampire, and found him different and interesting, mainly because he hunted other vampires. Since the game doesn't provide clans or quests (other than the cure quest) like Morrowind does, you need to rely more on your imagination and/or mods to find a place in Cyrodiil for your vamp. Mine wasn't in any guilds, and refused to feed on beggars (besides finding it unpleasant, he felt they already had enough to deal with), so he lived in Borderwatch with fellow Khajiit, and now and then he'd sneak into the guard quarters at Leyawiin and snack on the healthy soldiers, then run for cover because they're light sleepers :laugh:
Certain skills and attributes are increased more at each stage of vampirism, and you become more resistant to weapons. The first ability can also be used repeatedly. However, you also gain more weakness to fire along with receiving sun damage, and the other three abilities are Greater Powers, so they can only be used in emergencies. Doing something like the MQ would be considerably more challenging at 100% than 25%, but it'd be possible. Depending on how you play, it can be harder to stay at 50 and 75%; pretty much you're either a total monster, or just look kinda freaky. But the stat boosts can come in pretty handy, and the Hunter's Sight ability can be useful too.
The skills and attributes that are boosted aren't really specific to any one kind of character, but they do favour characters who'd rather slip through the shadows than charge into a fight.