I went in pretty much the same timeframe - Spent nearly a week in Dublin, starting on Dec. 26, which over there is known as St. Stephen's Day.
Unlike the UK, where it's Boxing Day and there are huge sales everywhere, St. Stephen's Day is DEAD. Just about everything is closed.. that included my hostel's lobby (Barnacle's Temple Bar Hostel - great place) - but by noon one of the nearby pubs opened up, and they were more than happy to let me store my backpack under the bar and guzzle down Guinness until the hostel opened up. On top of a lot of closures on that day, a lot of the little mom-n-pop businesses I wanted to check out on friends' recommendations were closed for the holiday period. The upside? It's not very crowded.
Dublin is EX-PEN-SIVE! Especially in the tourist haunt of Temple Bar, but in general, it's one of the most expensive places I've been to. Other than picking up sandwiches at a local convenience store or getitng a group together to make community meals at the hostel, eating in Dublin seemed prohibitively expensive. Drinking can be pricey as well, but what's nice is every pub has a posted list of prices, so no bartender can play screw-the-tourist and overcharge you for drinks. You can also scan the list for the cheapest drinks with minimal embarassment.
Places to See
There's plenty to see in Dublin that's free.. Museums, parks, etc. Keep in mind that the Book of Kels display at Trinity College will be closed around this time, but it's still well worth strolling around the campus and taking it all in. One of my most memorable day trips was Wicklow and Glendalough, which any hostel front desk can arrange for you via a small local tour company. Very well worthwhile. Also great are the Backpackers Pub Crawl (definitely a good, raucous time out, and cheap!) as well as the famous Dublin Literary Pub Crawl, which isn't as much of a party but definitely a great night of entertainment and a touch of education.
You'll find that just about every decent-sized pub/bar has live music... FREE. I couldn't believe how many places I walked into that had great bands - not shitty bar bands who do covers - with great original songs and amazing vibe. You'd think the whole country was made up of professional musicians. You can't seem to stagger around Dublin without walking into a free live music venue. If in doubt, just ask a local to point you toward one.
It's freakin' COLD there that time of year. Actually, it's surprisingly pleasant during the day, but it can get BITTERLY cold and windy at night. If you look at pic #95 of my Dublin photo gallery
, you'll get an idea of how cold it was for an American and an Australian on a night out