If a creature enters the battlefield as a copy of or becomes a copy of a creature whose dash cost was paid, the copy won't have haste and won't be returned to its owner's hand
It plays best with cheap creatures and fliers, but its just a generally high power level card
using a card like Jace, the Mind Sculptor to put a Time Warp or other extra turn spell on top of your library turn after turn offers infinite turns
But I think its fair to say that the disparate themes of enchantress, artifacts-matter, top of library-matters, and lands-matter left people with both correct and incorrect expectations for the product
In fact, outside of Legacy and Vintage, I dont think theres any Magic format that wont at least be testing this card out
Thanks to the variety of powerful cards that trigger during the upkeep such as Mechanised Production or Twilight Prophet Obeka can get out of hand extremely quickly