My short answer is no, not worth it, unless its unimaginably cheap. Our Irish experience is described below.
In early February 2010 my wife and I spent 7 days in Ireland for our "babymoon" (ie, last vacation before our son was born), mostly because it was super cheap, like $1200 for two people, airfare and hotels included, all arranged through AerLingus travel. (the "Castles of Ireland" tour.) It would have been $1150, but I INSISTED that we upgrade the rental to get a GPS. If I hadn't, we'd still probably be lost on backroads. Here's the thing: There's a reason Ireland was so cheap at that time of year.
The 3 days we were in Dublin it rained mercilessly, and it rained all or much of the other 5 days. Temps in the 50s but I mean GALES of rain. If SWMBO hadn't been almost 7 months pregnant, passing the time drinking in pubs might have been worth it...Dublin had some interesting museums and sites, but its a walking city, and walking around in e36m3ty weather isn't so much fun unless its to see things that you REALLY want to see, and not just because they happen to be there.
We also drove all the way to the West coast of Ireland, which was cool enough, Dingle peninsula and the cliffs of Moher were beautiful, but that was by far the best 3 hours of the whole week. Driving about 900 miles on bumpy, narrow country roads (ie, like 4/5ths of a car width) with a pregnant wife who at the time had a thimble-sized bladder...just not our best collective decision.
We saw some interesting things, but we've both travelled a lot and just weren't all that into Ireland, frankly. One of the strange things about Ireland is that it is extraordinarily tourist oriented, but not necessarily in a good way. One of the most overused words on advertising signs and such was "Authentic" (as in "authentic irish pub, restaurant, dancing, music etc.). We went to a couple, and were unsurprised to conclude that no genuine authentic Irish person would have been caught dead within 100yards of those places unless they worked there.
Now, if you're interested in the UK generally, I couldn't be more enthusiastic about Scotland. I've been twice, and it was awesome. Wife also did a two week walking tour there with her mom & sister and absolutely loved it.