Well, I've been in Dublin just over a week now, and have been doing some cycling more or less every day, principally to and from the City, and in and around Churchtown/Dundrum, the area where I'm currently staying. My commute to the city takes in Churchtown Road Lower, Milltown Road, Sandford Road, Ranelagh Road and over the Charlemont Bridge down Camden Street, ending up in Drury Street cycle parking facility. On the return I take a similar route but going back up Dundrum Road so as to call at the shopping centre on the way home.
In general, I'm quite happy with cycling in Dublin - cycling on Dundrum, Sandford and Ranelagh Roads is relatively smooth and comfortable compared to roads I've ridden on in other places I've lived, with wide cycle lanes and no real obstacles to going at a constant speed into the city. When doing it early morning there's a tendency to find delivery vehicles parked in the cycle lane, along with a few taxis and other vehicles, the same is true in late afternoon, but getting round them doesn't appear to be too much of a problem, although it would inevitably be better if they didn't. Milltown Road could do with some resurfacing, as it's quite bumpy and not a comfortable ride, particularly on a road bike, and the same is true of Dundrum's Main Street - rather bumpy and not much room for cyclists, really, though as it's one of the shorter, less busy roads in the city I can just about bear it.
One thing I've found interesting in this city is that the traffic lights go straight from red to green, with no orange light in-between - very different to the UK, but something I've adapted to quickly. To say my commute is 4/5 miles each way, it only seems to take 25-30 minutes max, and doesn't feel like a drag, which is impressive considering I've previously only had to travel 2-2.5 miles in the past. The only issue I have is that the commute to the city is all downhill, whilst on the way back it's all uphill - the climb isn't particularly strenuous, but requires a bit more effort at the end of the day! As for cycling in the city, I consciously avoid streets such as O'Connell and Westmoreland, and the quays if possible, as I simply don't feel comfortable cycling on them. My wish is for cycling to be a pleasure, not a chore, and I find those streets simply too busy and uncomfortable for my liking - they simply don't suit cyclists. For now though, I shall be maintaining my current cycle commute, and probably alternating it with taking the Luas once the money starts rolling more freely.