I didnt mind Dublin. See I suppose its all subjective. And perhaps a bit of luck with when you went, what was on, who you went with etc
There isnt much to do other than drink in Dublin. But thats much the same as Newcastle
Hamburg I went in winter, it was freezing and snowing (not necessarily a bad thing) but just found it a bit miserable and especially grotty. Didnt like the reepeebhan at all and the christmas markets werent up to much either.
Im not a huge fan of Amsterdam (although having been 5 times there must be something about it) but I definitely preferred it to Hamburg.
Absolutely love Germany in general though. One of my favourite countries. Maybe I just expected too much of Hamburg or went to the wrong places.