The GPS will work everywhere it can see GPS satellites. No problem in North America and Europe. You just need to make sure you can get maps for GPSDrive for the areas you will be travelling.
The only thing to be aware of is the startup time of the GPS. When you buy it it won't know where it is so it goes through a cold start. It's seeing the satellite information but it needs to establish where the satellites are actually positioned before it can do the triangulation to figure out where it is.
Cold starts really need as good a clear view of the sky as you can possibly give the receiver. That includes down towards the horizon as well as straight up overhead. Cold starts can take a few minutes. The better view of the entire sky you can give them on a cold start, the quicker they can figure out where they are.
Trying to do a cold start inside the house right after you take the receiver out of the box is going to be a frustrating waste of time. So have a little patience and don't bother trying your spanky new receiver until you can take it outside and get it a nice wide view of the sky.
If you turn a GPS off and travel a long ways, say an airplane trip, it will have to go through the same cold start process to figure out where you are.
Once the GPS receiver has done a cold start, it will start up much more quickly each time you use it after that, as long as you have not travelled a long ways since you turned it off. Just a few seconds to warm start is quite normal.
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