Flown through Holland many times. VFR, no transponder, no problems. Even got some help from military radar once when the weather was crap (and they let me fly through several MATZs to avoid weather). I would also recommend Midden Zeeland, nice airfield and very helpful people there. I've also been into Schipol VFR in a Cessna 310, again no problems as long as you stick to the published procedures (don't let the fact that there are hundreds runways put you off, it really is quite easy and good fun). Enjoy.