They just did some remodeling and rebranding and I forgot to get a shot of the new one. Now called premium air rooms.
But back when I could get in with IB, it's just a basic hotel style breakfast and you can get a shower room which is just the shower component of a hotel within the terminal. Personally, I went once and that was probably one more time than I needed.
But business on Iberia no longer gets you access so if you're planning on entering with that, it's a no-go.