The driver was late to pick us up, even though our tour guide was one time...so we left a half hour after the specified time, which was a bit annoying. However, on the way home, the driver was very accommodating and we were able to stop and buy some fruit at roadside stands and stop for a CR bathroom break which is why we wanted a private tour in the first place. Since it was a rainy day, the waves on the lake were a bit rough I think they get rougher the later in the day, regardless of weather, so we got pretty wet on the way back. The boat had plastic tarps to cover our legs, but we still got pretty drenched. I would recommend bringing an extra set of clothes to change into for the car ride home.
Also, Manila traffic was really bad, so we didn't get back into Makati until 6:15pm. So, with traffic, it was more like a full day than a half day trip.
Our tour guide up Taal was very accommodating as well. We walked, and found it very easy, although it was raining lightly. Definitely did not find it difficult, and my parents are in their late 50s/early 60s. The horses may be faster, but they don't appear to be treated very well they have people hanging off their tails, and they are quite small. Our tour guide also helped us take a few group shots and pointed our several scenic spots for us to stop at. Lastly, we were very impressed with lunch! It was a full meal - we each received a full tilapia, along with rice, chicken adobo, and vegetables!