Undead Servant is definitely below the curve, and despite the potentially high upside (which gets higher in Limited since you can run as many as you want) it wont always be worth playing
Im not excited to play a Warpath Ghoul or a Headhunter
The death trigger is highly relevant, since as part of the 99 you don't have to worry about it staying dead for long, and as your Commander you almost never have to pay the commander tax so you can build around the card without worrying too much about it
While not as oppressive or powerful as Sliver Queen or Sliver Overlord, it plays an exciting game nonetheless with options to be built competitively or casually
You net two spells cast for your instant/sorcery spell triggers like Guttersnipe, and you netted four cards and looked at eleven
Im not sure why it doesnt work with commanders, but there are plenty of other targets to choose from