I've used Arduino a few times myself during my studies. Nothing too spectacular though, using a IR-detection circuit to check if an object is near somewhere, and let the arduino perform an action based on this proximity. For this project I only contributed a part of the actual Arduino code/hardware used.
Also had to make a remote control car, controllable via wi-fi for another project, since I was the only Electrical Engineer in that project group I got to do a lot of the programming/installation of hardware such at the motors and servos myself. It did cost quite some time, but it was a lot of fun to do!
Overall I find Arduino very easy to use, however you just need a project .