Ive got to say bangor must be one of the best places to do a pub crawl! If you start at paddy's in upper bangor theres plenty of pubs up there to goto, then down bitch hill. Alternativley if you start in lower bangor in Piranha and work your way along if you find yourself going for a drink in every bar along the way you will defenitley be waking up with a hangover.
What bangor lacks in clubs i see the pubs more than make up for it.
The biggest difference you will see if you come from a big city will be how early places close, you will find the time you would usually be heading to a club will be the time your going home in bangor. Thats the major flaw from my point of view.