I bought a TS-E 24mm lens about a month or so ago, and have been playing with it since.
It takes a while to get used to how to get the most from it. Once you do so, it's incredible.
There are really four main uses for it (beyond the fact that it's a very sharp prime):
1. Being able to create front to back sharpness throughout the whole photo by altering the angle of the plane of focus (through the use of tilt) - a tripod is essential for doing this well (although I think some experts can get used to doing it handheld). The kind of scenes that have the most impact, and where the lens is most necessary, is where you have an object that's (really) close in the foreground - like a leaf, a stone, a log - that you want to have in focus together with your backdrop. There are tables which exist that help with the amount of tilt required for any given height off the ground/desired plane of focus (or to be more precise - perpendicular distance from the camera back)
2. Easy panoramic shots, or large megapixel photos, with no parallax issues (through use of shift)
3. Removal of converging lines - especially useful in architecture (through use of shift)
4. Miniature model effects (a lot of which could also be achieved in photoshop) by relocating plane of focus
I've done a lot of 1-3 and almost none of 4. In all events I've found I need time to take the photo; a tripod; when I'm doing front to back sharpness photos, a little table in my wallet of initial tilt angles to start from; and a clear head
But then, I'm not yet an expert. I find myself really scouting for what I want to take a photo of first - which I am told is generally a good principle.
Live view focusing is essential, helped with 3x3 gridlines and 5x magnification; that's taken a while to get used to, and ultimately I've set up a Custom Function shooting mode on my 1DX specifically for it. You also need to be willing to get down low, because it's these photos that have the most impact when shooting front to back sharpness - shoot from a height of 1.7m and you don't really need a tilt at all; shoot at 40cm from the ground and you need a tilt of 3-4 degrees.
But the manual focus per se is not an issue at all; nor is IS at 24mm
I found a great guide to help - you can find it here: http://oopoomoo.com/ebook/the-tilt-shift-lens/