Got mildly hosed by Angelic Overseer last night. That thing is a pain.
Not really. Kill all their humans, then Tragic Slip or (in any non-Standard format) Bolt the Overseer.
Basically, Angelic Overseer is a pain if your only removal is Plummet and friends. Otherwise, she's no worse than any other angel. Certainly not as bad as Avacyn or Sigarda.