If you're a person who can figure out transportation to and from the sites, this tour is not for you.
First off, coordinating pickup with Mary was not great. If she simply left it at the pickup locations on her website, it would be straight forward. When you try to book your tour, she makes you tell her where you're staying, then tells you where to meet the tour, like she would make arrangements to pick you up someplace convenient for you, it's a lot of back and forth. In the end, the pickup locations on the website ARE the only pickups, however, if you decide later to change your hotel, you must check with he's to make sure the pickup location you are expecting is actually scheduled for a pickup that day. Then, at the end of the day, there's one dropoff at Trinity College, no attempt to get you back where they picked you up. Also, at booking confirmation, she asks you to be at the pickup locations 25 minutes earlier than stated on the website. So if you're a person who respects other people's time and show up early anyway, DON'T show up any earlier than the time she sends you in the email, you'll be waiting for a while. I found the logistics frustrating.
Second, and my main irritation, is that when it comes to the sites you visit, it is NO different than if you'd have paid the site directly. Our guide, Martin(Mary didn't even attend our tour at any point), did not visit Knowth, Newgrange, or Tara with us to give us anything more than we got from the guides who work for OPW. I could have paid the prices OPW charges, which I think was like €16 per adult, €10 for my 6-year old, and NOTHING for my 4-year old and gotten the same experience at the sites. I also wouldn't be hostage to Mary's tour schedule. Instead, Mary charged €75 per adult and €70 for EACH child. Granted, it was nice not to have to worry about transportation to the sites, but I would have much rather saved myself the €200+ for public transport or a rental car. In short, I found this tour to be a "tourist trap".
Third, she tells you that you'll be stopping "somewhere for lunch". What she doesn't tell you is that it is a tiny "cafe" at a local farm with a cooler full of pre-made convenience store sandwiches in plastic boxes and bags of potato chips (crisps). It was pretty disappointing.
Our guide Martin was fine as long as we were in the bus on the road. He filled the ride with history of Ireland, neat factoids, and a good ammount of humor aimed at all the lore surrounding the history of Ireland. But we got relatively nothing from him about the sites we visited.
If you don't need someone to drive you to/from the sites, do yourself a favor and be your own tour guide with your own itinerary, you'll come out ahead.