A broad question to answer... your Arts classes will vary, of course.
For ARIN UoS, ARIN1000 is just about the most boring class I've ever done (in the Arts faculty), but the other ARIN classes are much more enjoyable and the lecturers/tutors usually easygoing and approachable, though sometimes disorganised. Some classes are practical, like ARIN 2610, basically a web-design-like class -- if you've done web design or learn quickly, do this one in 2nd semester, 1st year, even though 2nd year is more usual. Other classes are theoretical, such as ARIN 2620, which is somewhat sociological in nature, but more accessible, e.g. one of the lectures looks at The Matrix.
The only INFO/ISYS class you'll do in 1st year is probably INFO1003, a crash course in Office, Javascript, HTML, etc., and leads in very nicely to ARIN 2610 if you've no experience with these things. INFO/ISYS UoS are of course more technical in nature, but the practical bits are tolerable enough. Level of maths is irrelevant, but logical thinking is a plus. INFO2110 and INFO2120, second year units, seemingly jump in difficulty from 1st yr. A lot of B AI/DTC students doing INFO/ISYS find the differences between Arts and INFO/ISYS UoS difficult to overcome -- different types of learning, different types of cultures, different types of people. Imagine going from something such as a history class to studying the intricacies of databases! If you can balance all that, you'll be fine.
One thing pertaining to the course... if you're planning to do only one Arts major, you've nothing to worry about. However, if you're feeling ambitious and planning to do either two Arts majors or one Arts major and a Sci/EconBus major (both with compulsory IS major, of course), plan carefully which UoS you want to do, and when.