I use the train a lot. This week, I took 8 intercity trains. Ever since I started working on my research in Trinity, I've spent at least 2 hours a week on intercity trains, and usually more. So it's the form of public transport I'm most familiar with, and thus likely to be my most reliable review.
I think trains are the most comfortable out of all the public transport options. The seats are soft and roomy enough (for someone my size, anyway), and there are handy tables in groups of four facing seats if you want to get some work done or have a chat with some friends. The journey is very smooth too. One gripe is the large penalty for putting your feat on the seats - doing that is very comfortable, and wouldn't do that much damage to the seats. Also, in the Dublin stops the train is often too crowded to get a seat, which is unpleasant.
Miscellaneous, but there are really good views out the train window on my usual route, since it's almost all coastal.
The train is generally a pretty slow mode of transport, and artificially so. It takes an hour to get to Dublin normally, but only about 34 minutes on the express. But the express trains are quite rare, and I don't remember ever landing on one without specifically planning it. You can drive to Dublin in about 75% of the time, assuming light or no traffic.
Let's be real here: train stations are in the middle of nowhere. There's only one station in most towns (loads in Dublin, but that's Dublin) so they're unlikely to be near your specific location. Usually I have a ten- to twenty-minute walk to my destination after getting the train. Their reach is obviously longer and further than the Luas, DART and Dublin Bus, but not as detailed.
Ease of Use
The train loses out here in comparison to DART because missing your train or your stop is a big problem and can be catastrophic. Trains between Drogheda and Dublin (my route) usually go once an hour, so if I miss one by a couple of minutes I'll be late for my meeting if I wait for the next one. There have been tears. Stops are further apart too, so missing your stop is a big deal. Tickets make little sense - at my station, tickets cost about a third more if you buy them before half nine, and my ticket always stops working on the return journey so I just wave it at the security guard.
Ease of Use: 2/5
Trains are relatively luxurious, so they score highly on facilities. Wifi, luggage racks, desks to work on are standard. Some trains also have plugs and food carts, which make me feel like I'm in Harry Potter. Not much to it, really - trains are great here. Quality.
Train cost is great if you can get a child ticket, €7 for a return trip to Dublin without even having a leapcard. But an adult ticket often costs literally double what the child ticket does, which is crazy. For 2 weeks in July, people 18 and under can travel free with a LeapCard, which I think is awesome. I really need to get a LeapCard. So I'm conflicted here. Better than bus, but worse than Luas.
When I totted this up originally the train got 20/30, but I have too high a sentimental attachment to it to allow that, so I'm bumping it up five points for the enjoyability of train rides. Bam. I'm God of this blog.
25/30 = 83.33% = B1