I recently started a vampire character and though I have enjoyed it from a RP perspective the actual gameplay side was very lacking. The vampiric drain was pathetic at lvl 2 and at lvl 10 there was no point in even having it anymore. The vampire lacks content. It is obviously a tacked on addition just for RP purposes IMO.
Yes, vampiric drain is a huge failure on Bethesda's part, either remove the magic requirement or boost the drain. Also, remember if you are a vampire, you are undead. That means if you learn the necromage perk in the restoration tree, ALL spells casted on yourself and ALL enchantments and even potions are significantly boosted. A pretty nice bonus for being undead, don't you think?