i've been to kenya. i went to study environmental law and trade with my law school (between first and second year) and interned with the UN environmental programme. i generally enjoyed the photo safaris, but there were aspects of it that i didn't like.
1. whenever we would come upon an animal doing something interesting, the drivers would radio other drivers and the whole area would be swarmed with vans full of tourists, which put stress on the animals.
2. i felt like i was living behind a lense, unconnected to the earth and the animals. this was partly due to my companions. we would ride in the van, they would take more pictures than they would actually look at the animals, and there was a consumer aspect to looking at the animals. seeing little birds was not enough for them--we had to always see the big five--so the driver would drive around like mad looking for the big five so we could check list at the end of the day: saw this, saw this, saw this. It's not a great way to observe and explore animals in their natural habitat.
similarly, people spent more time taking pictures than actually looking at the animals--and would say to me 'if you're not going to take a picture, would you move so that i can get one?' basicly pushing me away from my little spot of observation.
the best tours i did were the walking/riding tours. i was able to do one brief camel tour/safari (about 2 hours total) which was really interesting. I did three guided hikes--just me and the guide because no one else wanted to hike ("it's not likely you'll see the big five!"--well, that's not the only thing that lives in kenya, thank you! i did see some really interesting plants, insects, reptiles, and birds). And i was able to do one horse-back safari.
these were the best because the groups were small (4 camels, one with guide on it; me and guide for hikes; five people on horseback, one with guide--and no one took pictures, talked much, or did anything stupid like throw things at the babboons).
if you're going, i highly recommend going on these sorts of safaris in addition to the ones in the big vans/jeeps. i also recommend going to the various little private preserves where you can help feed the different animals. I was able to feed giraffe, wildebeast, rhino (baby), elephant, juvenile lions, etc. these are not zoos, but places that take in rescued orphaned animals and strive to release them. it was really neat to be that close to the animals, to learn about them, and to learn about the work that the various preserves were doing.