Ireland would be a great place to pursue an MBA, but I'm not so sure about Griffith College. It certainly isn't a program that most employers around the world would have heard of when you go looking for a job.
In addition to the value being decreased by it not being a well regarded program, it could be hard to gauge the quality of the education you will receive. At the very least, your fellow students probably won't have the same qualifications as those you'd be working with at a bigger/better known program.
If you could get into the Trinity or UCD MBA programmes, I'd go with those. Both are highly ranked and offer a great education. There are also some very well regarded online MBAs.