I went on the 9-day tour at the beginning of June. Overall, this was a great way to see Ireland, especially for someone on a budget. I got to skip the stress of planning and of driving around Ireland (some of those roads are killer) and going with a tour allowed me to get to know my fellow travellers. Our guide Barry's local knowledge meant that we got to see things that we probably wouldn't have travelling independently. It was definitely a tour that focused on nature, which was just what I was looking for. We did walk around the cities a bit, mostly in the evening, but if the cities are your focus, you'll want to go on your own.
The hostels were adequate, nothing exceptional, but there's always the upgrade option for those with a bit more money, though I will note some of the B&B locations were not as central as the hostel locations. The breakfasts provided consisted of toast and cereal (sometimes just toast) so I recommend visiting a grocery story in the evenings to pick up something for breakfast. It's also a great way to save money on lunch and dinner, though you'll want to eat out at least some of the time and try the local foods. And whether you drink or not, don't pass up the local bars with their live Irish music.
Our tour guide and driver was Barry. He was a great guide. Very knowledgeable, good sense of humour, and took pride in going the extra mile. I especially love listening to him tell the myths and stories of Ireland. The schedule was malleable to a degree, depending on our preferences, because the 9 days gave us some extra time.
The tour group was great too. There were only thirteen of us for the first half and we really bonded as a group. The smaller bus is definitely superior to the larger bus. If you can manage it, definitely go for a tour with less people.