What are your options when the discount period is finished? Are you tied to ICS for a period at a rate of their choosing?. I presume that if the variable rate rises, as does the rate you will pay? Is the 2.9% rate the nominal rate or the APR? What tracker rate are ICS willing to offer for the same term and amount borrowed? Did the broker discuss any other options with you?
On the face of it, it does appear to be a good deal. Get your hands on yesterday's Irish Times and have a look at the Property Supplement-all rates available direct from the lenders are listed, so it's a good way to make comparisons. If you have looked around and are confident you have a good deal, go for it.
Edit: As Sarah W has pointed out, it is a good deal in the short term, but thereafter ICS may not be the best option. You need to take a longer term view than 2 years.