Is DBS poor? Well, it depends on your own expectations and standards.
I'd say doing a postgrad anywhere outside the top 5 is nuts. At undergrad, outside the top 10 is very chancey and ideally, you want to be in the safe and sharp end of both.
If you're a top performing student, DBS will probably feel a bit disappointing when you consider the quality of employment opportunities available from other Business Schools or Universities with significant links to the City in Europe (LBS, CASS, LSE, Said Business School etc)
When you're an international student, you've got to look at the USA too - at which point, DBS is seriously looking like a near nobody.