I've played the birdy to great effect in my former Alesha, Who Smiles at Death list, which was pretty flyer-heavy. Keeping mana open usually scared anyone but go wide token lists away. As mentioned, even small flyers amount to considerable amounts of mana over time.
It was also part of my initial Teshar, Ancestor's Apostle list. But it wasn't as stellar there. There are plenty of cards that reanimate Weenies for less mana, dozens with faster influence on the game and plenty that don't come with requirements for saccing.
Not exactly. Soul Snare can only exile creatures attacking you/PWs you control, which is a very limiting factor - especially when you telegraph it, being an enchantment and all.
Lieutenant Kirtar has a lot more political value, since he can exile any attacking creature. You can even assign him as a blocker for one attacking creature, then exile another one before combat damage is dealt.