.NET Gadgeteer compatible WiFi module integrated antenna or external antenna

Does the WiFi module with integrated antenna works well in most case? or I should choose the external antenna type?
Any suggestion?

I have experience in using XBee integrated chip antena and I don’t recommend it. I find it useful only if you want to do tests on your desk when modules are right next to each other.

The answer depends on what “most cases” is. As Gralin implied, you will always get better performance form an external antenna. The added antenna is inexpensive and mounts easily on an enclosure, so my suggestion would be to use it. You may find it is not necessary, but that is better than finding out your embedded antenna doesn’t “go the distance”.