I was planning on making a vampire lord illusion assassin build. my plan is to major in sneak, illusion, one handed, and archery (one handed for armsman, and archery mainly for steady hand and eagle eye). My stat ratio will be health 3, magic 2, stamina 2. my main question is this: Can I be an assassin and still enjoy playing as a vampire lord? I'm not really a pure mage type character, as I've spent most of my time playing stealth characters, but my friends seem to think they are geared more toward mages. I on the other hand, think that a stealth character could benefit from it, but I'm not entirely sure about it. if someone can confirm this it would be greatly appreciated

honeslty I think theres little point in being a vampire as a pure caster, a vampire has all the weaknesses and strenghts that a pure mage already has... so I honestly dont see the advantage over being a werewolf, wich has ALL the advantages the mage does not have, wich is, being a melee god.
obviously both transformation are a matter of preference nut there are obvious synergies that either support or complete certain builds better than others.
lets see what you get as both sides
Vampire-human form:
-bonus to sneak skill multiplier
-bonus to illusion level caps (only usefull at low lvl to non illusion perked chars tbh)
-immunity to disease/poison
-night vision
-drain life spell (useless)
-seduction power (useless except to feed, it makes you able to feed on low lvl npcs as if they were a vampire manor cattle npc)
-invisiblity power (late stage only)
-raise dead (usefull but not terribly so)
Vampire-lord form:
-fast movement speed (in caster mode)
-medium boost to stats
-short range-weaker-slower melee attacks (melee mode)
-medium armor
-teleport spell (very good to fight against dragons and ranged oponents in open ground)
-strong ranged aoe drain life spell
-grip spell (situational but fun)
-paralysis spell
-raise dead (usefull but not terribly so
-summon gargoyle (strong summon)
-general utility (like sonar ability and stuff, not very usefull at all, just cool)
NOTE: weaknesses to fire dmg are very taxing if you cannot counter them, and not being able to be at top performance during daylight also is a big con.
Werewolf:
-no changes in human form, no advantages and no disadvantages
-fast movement speed
-large boost to stats
-short range-stronger-faster melee attacks with high knockback chance
-heavy armor armor
-high hp regenration (if you kill alot or have already a few corpses to eat)
-aoe fear howl
-summon wolves howl
Note: shorter duration and only once per day, BUT with perks you can turn a single transfomration VERY long as you feed.
anolysing both, I can see that vampires get ALOT more stuff, but most of it is either useless or directly more apropriate or usefull to stealthy chars... why? well for one the fact that they naturally prefer to act in the night, makes the daylight vulnerability less bothersome, the nightvision much more welcome (other chars will use ligh spells or torches tbh as they dont need to worry about being illuminated), the stealth bonuses more welcome and the invisibility spell more welcome.
also the vampire lord form, allows them to access a totally different playstyle to what they do in human form, wich is mainly spell caster but also they are able to mlee to some extent, they wont be doing more dmg than with their dual weilding daggers/swords but they will for sure, last much longer in 1v1 against though melee oponents thanks to the faster speed to even light armor, and hp regen from bats and life drain if they need.
a warrior type can get the same benefits from vampire lord, but not really in human form, in fact both the fire vulnerability and daylight limitations afect him much more than a stealth char, a stealth char can do assassinations just fine without worrying about his stats because he avoids melee combat alltogether, a warrior doesnt.
but sure if you dont mind those downsides and cope with them, its a pretty cool choice too.
but a pure caster? theres not much vampire form does that a caster doesnt usually builds itself to do already, you are already fast, are bound to have better either/or/and summons, CC, heals, ranged nukes/aoe etc.
the human form pros are pretty useless for a caster aswell, the illusion bonus will allow you to use the lower rank spells for a while longer on low level stages, but nothing after that unless you perk illusion anyway, and if you do perk illusion the perks alone are more than enough to keep the spells effective.
standing in melee combat however, is something no pure mage can ever do, so for me, werewolf for a mage all the way, vampire for stealth chars all the way, and maybe warriors or warrior-caster/stealth hybrids.