I've done LAX-DUS & DUS-LAX as well as TXL-JFK in airberlin economy.

The LAX-DUS isn't so bad as the adjustable headrests are nice for sleeping. Neither leg will be fun if you're taller than 5'9 though. That's how tall I am and 11 hours in that tight pitch is a bit much. JFK-Germany is manageable as Gus2013 said.

I would generally stay away from row 36 however as it seemed that on all my flights people would crowd near the lavatories. I think the ratio of seats to bathrooms on airberlin is much lower than other airlines so the bathroom areas tend to stay busy which would be disturbing to me.