Believe they're doing ok. Their May passenger figures averaged 71% with Milan their worst route at 55% and Malaga their best at 85% (Source CAA). Also they have a very good product, having flown with them to Palma, and their on time performance seems very good too! I believe they keep a spare ac available to cover for the 3 ac required for their current route structure. I'm sure they'll go from strength to strength and would have done even better had it not been for Planetair starting up a lo co at around the same time ex LBA. Looking at their website
www.jet2.com/cgi-bin/jet2/I6/home they have a lot of flights full to/from Malaga and Palma this month so they seem to be growing their routes nicely. Going to AMS with them in Sept cost me return plus taxes (one of their specials) so I hope they're still around!