In 2004 I flew with BMI from London (Heathrow) to Dublin. It was not the cheapest airline to fly from London to Dublin, but it was a very nice airline to fly on. The trip over to Dublin is a very quick one. It felt like we took off, we were in the air for about 30 minutes and then we were coming in to land at Dublin.
The service on the flight was good, the seats were very comfortable as well. On BMI you are offered food and drinks (included in price of ticket). On the morning flight, like the one I went on, we were offered juice and panini (on the website it states that a traditional English breakfast is also offered, but I cannot recall if that was available on my flight or not).
Prices for flying with BMI are okay, it just depends on what time of day you are flying. Their earliest flights are usually their cheapest.
On their website you can match flights with finding a hotel or renting a car (or both).
If you're arriving from a continent like Asia, there is (sadly) no direct flights to Dublin. You have to fly in via London's Heathrow Airport. The pic I took below is of the British Midlands Business Class Lounge at Dublin Airport. Actually the BMI lounges look the same all over the world.
BMI has the most attractive rates on Business Class compared to Aer Lingus. My ticket costs slightly over EUR250 for a return flight (LHR-DUB-LHR) vs Aer Lingus biz class fare of EUR 490!