It depends on your area of interest. In some areas UNSW is competent. For example, I have been quite satisfied with what they offer in the way of philosophy, in particular UNSW is strong in certain areas of continental philosophy (of the 20th Century European variety) which are of great interest to me. Compare this to, say, non-classical systems of formal logic or American pragmatism of which UNSW offers little. On the other hand, I just made a post in response to a student interested in political economy (PECO) saying that while I thoroughly enjoyed the PECO units on offer I would recommend any student seeking a thorough education in heterodox (read: alternative) approaches to economics/policy to consider USyd which is much stronger in this area (i.e. they actually have a PECO department).
In general Sydney University is much stronger in arts. They have more faculty members and, as far as I can tell, generally have more diverse course offerings and more areas of study (and more potential supervisors for a broader range of honours projects!). My personal feeling is that an arts hopeful who is unsure about the direction of their degree would be better off at USyd which offers much more choice. People may joke around and refer to UNSW as 'Kenso Tech', but the grain of truth is that the position of the arts faculty in the university reflects UNSW's history as a technical college.
As far as I know - from BoS, anecdotally, and from experience - intelligent, high performing students wanting to pursue studies or a career in the humanities typically opt to study at USyd
unless UNSW offers a combined degree in an area of strength, e.g. law, commerce, medicine, engineering, and certain areas of science (though of course there are other reasons which I assume are statistically less important such as geography, family, etc). This is likely what the interviewer you mentioned meant about arts/law students. A high proportion of the high performing students which bolster the arts faculty are provided by combined degree programs, notably BA/LLB (BA/MBBS, on the other hand, is negligible in terms of size). While I cannot fully substantiate this claim, I would predict that you will find more high performing arts students at USyds, which in my experience amounts to more stimulating tutorials and learning in general. Irrespective, both universities will always have their share of passionate geeks and dummies looking for a three year holding-pen.
In short, arts at UNSW cannot fully compete with the likes of USyd, UMelb, Monash, etc... but it is certainly stronger than non-
Go8 (UWS, Notre-Dame, Newcastle) universities and is perhaps moderately competitive within the Go8 (say versus UWA or Adelaide). At the level of Australia UNSW is a good place to study arts.
I know a number of people in the international studies program at UNSW, almost all of them in development studies, who have given it a positive review. It would seem that UNSW int. studies is somewhat in vogue (and so is perhaps less plagued by the above problems?) but nonetheless is dependent on arts faculty teaching and candidature across languages, politics, sociology, and so on. To a certain extent the teaching in politics at UNSW receives a boost from its strengths in commerce, law and medicine (think things like policy, international law, HIV and human rights). Do you have any particular interests within international studies?
My two cents.