We booked three day trips with Tierra Tours.
1. We day tripped from Granada to Ometepe. Our guide, Luis, met us at the ferry in San Jorge. He was friendly, knowledgeable, and very keen on showing us around the island he grew up on. We didn't feel the tour itself had too much to offer. And for the price (~$110 per person), it definitely was not worth it.
2. We joined the Masaya tour from Granada. Gustavo, our guide, was great. The tour itself is fantastic. We visisted the Masaya Volcano, an artisan market, had lunch at a lookout point, and visisted a ceramics shop which provided a demonstration. The tour fee also includes a beverage at the market. This was a very, very good tour.
3. In Leon, we took a cooking class through Tierra Tours. We went to the local market with our tour guide, where we bought the ingredients for the stew we were making. (Note: you also have the option of making iguana soup.) From there, we went to a local family's house and spent a couple of hours cooking. It was a great way to spend the morning.
The staff at the Granada office are extremely helpful and nice. Another great thing about Tierra Tours is that the price you pay depends on the number of people who have signed up (the more people, the cheaper the price).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.