We did the safari dinner and the Illuminations dinner.
Safari dinner: the experience was great and the food was good although we had a few people get ill that night from the spices in the food. So if any in your group have sensitive stomachs not sure it's a good idea.

But the safari experience was great as we got to see some animals better and long enough for a good picture compared to the daytime ride.

We got to do a meet and greet with 2 characters and they had some animal handlers with animals outside as well. Since it is 2 TS I'm not sure about value. We had Deluxe dining so it wasn't a big deal but on the regular plan I'm not sure if I would have thought it worth it.
Illuminations dinner: We got off to a bad start with this one but it did improve.

They had people checking in outside but you couldn't go inside to wait until your group was being seated. You had to wait until being seated to go in. It was extremely hot that day and my kids were wilting and to have to stand an extra 25 min. in the heat seemed ridiculous as they had a large enough area away from the tables where people could have stood and waited. I have to imagine if it were raining standing outside for 20 min. may have left no room for improvement in my mind.

But, we did enjoy the dinner and after letting our waitress know just how hot and thirsty we were she kept the drinks refilled.

I thought the food was better here than the safari and plenty for sensitive stomachs. So no sickies this night.

The little show they do with the kiddies was cute. The meet and greet with Goofy and Minnie had a Photopass photographer there so that was nice. The desserts at the Illuminations viewing weren't really that impressive but the kids enjoyed them. Although it was hard for the little ones to eat while standing up and holding onto their plates. (The adults in our group held the drinks for the kids.) The view was nice and overall the experience was fun. But it is 2 TS so on the regular plan it would be a hard sell to me when I could get 2 nice dinners around Epcot's WS.
I think between the 2 the food was better at the Epcot one but the experience was better at the safari.