I've mixed views on Metro North.
On the one hand, we definitely do need a rail link from the airport, with a regular, reliable and uninterrupted service.
It makes sense to me that there should be various stops along the way, rather than just a start and end point.
That said, I think its completely unnecessary to run most of it underground -this just seems like a slower and more expemsive way of designing the rail lines.
I also think it's insane to be bringing it through the city, to connect up with Dublin 6. The only thing that comes from this is a nassive additional expense, just to keep the good people of Rathmines and Rathgar happy. It should connect with Connolly Station, where there's a connection with Dart, Luas (Red line) and many suburban trains, incl. The Enterprise to Belfast.
We could also build an extension to the Dart line from either Howth Junction, Sutton or Malahide and connect that to the Airport. Again, no need to consider any underground options, it's too expensive and slow to deliver.
Anyone suggesting running lots of busses to and from the airport needs to consider limited road space, the need for drives, the likely pollution, potential for delays caused by road accidents etc. It's not the right answer, imho.