I visited Penelope two Sundays ago, in the Scandal party, and I liked the place a lot, apart from the party, that was wild! It's not as big as Amnesia, Space or Pacha, but it's bigger than El Divino. I'm sure it'll become one of the main clubs. The parties and drinks are not so expensive in general.
The layout reminded me a lot of Pacha: the main room surrounded by the balconies on a mezzanine, the stands, etc, and it has other small room on the mezzanine with big windows from top to bottom, from where you can see the whole big room. And just on the other side, windows with views to the street and the old Ibiza town and Dalt Vila. The main difference is that Penelope is darker, more industrial than Pacha, which is very white. The lights and sound systems were very good too.