Text as it comes, and then extruded doesn't always deform well because of it's topology. It won't have a neatly subdivided face. Straight lined characters like T, L or E (depending on font) will have few vertices and won't bend well. Curved letters like S or C will have loads of vertices, but it makes the face from long skinny triangles, so that can make for an ugly deformation too.
To get a nice geometry, you may have to actually poly model the letters, it's more work I know, but will work better if properly done.
Quick cheat, use Garment Maker to make the text object into an evenly subdivided surface, then Shell to make it solid. The downside to this is the random Tri mesh from garment maker may not always give the desired look either in some cases, but worth a try.
A nice quad mesh with sensible edge loops is what you want ideally. Then you can bend, twist, path deform or whatever, and subdivide further with Turbosmooth if you need to.