Every time I have visited this facility I have been treated fairly and received efficient service. Admittedly, I am more than a little familiar with traffic laws and the role of the Secretary of State in IL, but the people in this office are better than most in that they are patient, generally kind, and efficient. Other local facilities (looking at you, Bloomington) are far less well-managed. Also, probably because of the international nature of Champaign-Urbana and the relatively high need to drive around here, there are often many people waiting to take driving tests. If that is your sitch, get ready to wait.
As an aside, in IL, it is not called the DMV or BMV. The Secretary of State has many, many regulatory and other duties, including motor vehicle licensing. This is actually one of the things we do right, and is a big cost saver, believe it or not.
If you have to head over to the SOS, it is highly advisable that you check out www.cyberdriveillinois.com to find out exactly what documentation you will need to do whatever it is you are visiting for. Since this place is located BFEast Mahomet, it is a huge PIA for most CU folks to make a trip home to pick up a utility bill in your name with an address on it, or whatever, so let your fingers do the walking first. For the "easy" services, you can get in and out relatively quick, but I would still bring a magazine or smart phone just in case, and I would not plan a visit on your lunch break if your boss is bitto about being back in your desk by 1pm.
Also, for some transactions, like those where fees go to the Dept of Revenue (title exchanges), you may need a certified check or a money order. You can get these very cheaply at the big post office just north of Bradley on Mattis.