I only had to change once actually, at Utrecht. Took 2h44m in total.
Youve reminded me about buses too, better to buy a day ticket, it costs €5.50 or so compared to a maastricht - airport single which is €4 and allows you then to get any bus all day long, great if your going into town.
Oh and also, the bus time in the documentation is wrong (or at least was last month), make sure you ask at reception about the bus to get. There will be a group of you and youll probablyl all be on the same bus!