At least the Jungle Book was set in a lush tropical rainforest, and the Bandar-Log looked like a real temple. I don't think the hand-drawn original animation really did the rainforest as much justice as the CGI effects. I liked the scenery a lot, I felt like I was really visiting the rainforest. The sheer size of some of the trees was magnificent and really added to the feel of things.
But the savannah...is a big, flat place. I guess Timon and Pumbaa live in a rainforest, but they already did that with Jungle Book, and it's supposed to be a fun and happy jungle - not a massive, challenging place. I guess it would be cool to see the interpretation of Scar's underground lair, but omitting the Be Prepared song pretty much negates all of that since that's when you get to see all of the smoke and steam and green glowing geysers.
The Jungle Book was visually lovely, but I don't think Lion King will make for the same kind of experience. Plus, the Lion King was much more musical than Jungle Book, and making the animals all realistic will hamper the ability to have fun musical numbers with cartoonish movement and dancing.