Yes I did see that when adding, of course t he opponent(s) would be losing 2 creatures! I did consider just using one of the menu legendary black vampire I have, but sheoldred is too much fun, with swamp walk and recursion but in!!
If I was to lead with a vampire, I think it would be anowon, or kalitas!
Not saying you should change commander, but keep in mind that Sheoldred comes with some major downsides.
1. She costs 7, which means when she's inevitably removed, you'll need 9 mana just to cast her. Due to how little mana rocks/ramp you have, she'll very rarely come out before turn 7, and by that time people were probably saving their removal for your commander.
2. She's a high-priority target, so expect her to be removed often.
3. She has to live a whole turn cycle before she benefits your board.
If you really want to make use of her, you may want to consider adding some cards that can protect her (like
Lightning Greaves,
Swiftfoot Boots, for example).