I never visited Dublin, but spent a couple weeks in Ireland and had a great time.
One thing you notice is that the countryside is very very green.. almost unnaturally green. That's probably because of the second thing you notice, which is that it rains a lot! There are castles and ruins everywhere, you pass them every mile or so. They are on the Euro, so for some reason things are more expensive than England. The people were exceptionally gregarious - when you go in a pub everyone is your best friend and wants to buy you a pint (always return the favor though, from what I hear
As far as Dublin goes, I've heard a lot about the tech business booming there, lots of local freelancer interface designers work for Irish startups. There's also a Googleplex with many CA transplants.
Design wise, Guinness is a huge local brand and the brewery is landmark famous in the branding world. In the museum there's a striking observation tower extension to the brewery that's a modernist take on the frothy head of Guinness.
I've also heard there's an amazing illuminated manuscript/book that's supposedly a must see when you visit. Can't remember the name..
Anyway, hope this helps. And dude - if you happen to be doing business in Bristol again, we should definitely meet up!