Mostly very good. They're the firm my co-op recommends and I've used them several times for various fixes, some more complicated than others. They seem to have two levels of electricians, one for simple fixes like replacing light switches or fuses and one for more advanced wire problems. All in all they've very efficient, straight forward with their billing and helpful.
One apt with them I give a more mixed review where the electrician seemed puzzled and I watched him test the exact same thing 5 or 6 times, on more than one occasion. The definition of insanity being someone who does the same thing over and over again and expecting a different result, I found that troubling and while I've had that electrician in the past and he's been very good, he struck me as a little senile this time.
Finally, after about an hour of testing the same thing he looked at something else and that turned out to be the problem, so the end result was good, but I found his work on that day a bit troubling. Overall, still a 4 star company easily. Mostly they're efficient and very upfront on costs and their prices are fair.