Apart from the amazing £28 offer a few years ago (and the Lidl one later), I've always found Air Berlin to be more expensive than Ryanair.
I thought Air Berlin's entry on to the Stansted-Alicante route (a regular commute for me) was interesting but it didn't last. A pity.
It also has a frequent flyer scheme and a hub-and-spoke operation out of Palma.
So, in many ways Air Berlin doesn't really look like a "low cost" carrier in the easyJet/Ryanair mould.