The combined degree of engineering and commerce provides a great opportunity to gain a multidiscipline education in some of the most interesting and sought-after professional fields. As there are many faculties within each department, and many subjects within each discipline, there are countless combinations of specialisations possible within B Eng/B Commerce.
In first year there are not a lot of choices in subject matter as both degrees have a substantial number of core unit subjects in a range of different topics that are prerequisites to 2nd and 3rd year subjects. This is not necessarily a bad thing as it gives first year students a great opportunity to make friends with other people doing common classes.
Although there are many positives from considering a combined degree there are also many challenges. For instance, in later years clashes between classes are very common. Though this does add a little extra stress and require slightly more organisation, it is not the end of the world and most students manage accordingly.
The administration of the degree is done through the engineering department and in most cases the commerce department will wipe their hands clean of your coordination issues. Hence it would be very wise to find your engineering departments undergraduate assistant (in civil it is Cynthia Papangelis) they will save you amazing amounts of time and frustration otherwise spent chasing directions from people who simply don't want to deal with you.
Finally, pick up from the co-op bookshop a little textbook called 'little blue book'. It is a really well written summary of all first year maths subjects that they conveniently forget to tell you about till second year. It is 10 bucks and will save you a bunch of time because the maths department notes are notorious for being hard to follow.