Depending on immigration lines, you should be able to get into town with very little hassle/traffic; 11-11:30 pm ETA is not unreasonable. The real question is what to do at that time of night...except for the clubs/bars/red-light district, there isn't much to see at that time of night, and you need to head back to airport before 10 am.

The night life is famous so if that interests you, then go for it. Otherwise, get a good night sleep at hotel and visit in the future.