I only had one day in Delhi and did the tour to Agra. The driver was great, and the new highway was nearly empty -- took only about 3 hours each way.
The tour guide was average. He spoke as if he had a script with little intonation/feeling in his voice, so it was pretty boring. He did take great photos of me without my having to ask, which I appreciated.
Lunch was also average, at a pretty bland restaurant.
Overall, worth it to see the Taj Mahal but overpriced based on the quality. As a female solo traveler, I did feel very safe the whole time, and Amin was lovely.