I have an Ikea kitchen (3 years old now) and am delighted with it.
Their room planner is great, but definitely go and see them in the showroom, you need to have a proper look at the doors and handles and what not before you decide. Also, they have room-sets of full kitchens, so you might get ideas and want to change your design. (Whatever you do get deep drawers in your base units, they are so much better than normal cabinets).
Any of the threads and or posts on here relating to the Belfast Ikea kitchens are totally applicable to the Dublin one, the products are exactly the same.
Mine was installed by my general contractor as part of a larger job, and the carpenter said he was very impressed by the quality of the units.
You do need to make an appointment with the kitchen department when you buy your kitchen - but ring well in advance as they only have a few slots each day. They will design it with you from scratch, but if you already have a design you upload to their website, then they download it in the store and go over it to make sure you haven't left anything out. But it's really worth going on a "go see" visit before the day you order.