Imperialism in North Africa was negative in the way that it replaced traditional tribal culture, bureaucracy and religion with a foreign set of values, culture and way of doing things. This is one of the hallmarks of imperialism all over the world, and wherever it occurs it has profoundly negative consequences precisely because of the way in which it imposes a set of values and culture that is so different from the indigenous culture and religion.
However, at the same time, in spite of this massive negative issue, it is possible to argue that imperialism did bring some benefits to North Africa as a result of the efficiency and organisation that greatly benefited such countries as Egypt. Certainly Egypt prospered under British rule thanks to the efficiency and bureaucracy that the British imposed. Imperialism, although being something that I would classify as being overall negative for the countries involved, did have its short term benefits. The problem always seems to be what happens when those countries declare independence and try to self-govern.