Dunkerque is a nice little field.
The biggest trap is that it is not available for foreign aircraft to land at. In fact, only aircraft based in a few of the local French Departements can use it at all.
I'm guessing that you were aware of that and have found a way around the restriction. If so, beyond that biggie, not too many traps. Be aware that no customs service is available, so you will need to clear inbound and outbound via Le Touquet or Calais. If Calais, you need to make sure that you fax your details to the number in the AIP 24 hours before the flight (both directions).
Watch out also for the Nuclear Power station to the east of Calais at Gravelines.
The airspace looks worse than it is. Weekdays, reckon on working Calais followed by Koksijde. Weekends, you are more likely to work Calais followed by Ostend, who give a passable impression of a RIS, even to VFR traffic.
Look out for some serious microlighting action to the North of the main strip. There is a school there for tent pilots, so they don't always stick to the pattern!