Yes, italic fonts are not just slanted versions of the typeface. However, more simply slanted text doesn't necessarily look bad and has its uses. I prefer slanted Roman for long blocks of special text as I find it more readable.

Here is a sample illustrating Computer Modern’s Roman, italic, slanted, and “unslanted italic” fonts:

http://www.cs.toronto.edu/~murray/tmp/slanted_vs_italic.png

It’s sub-pixel rendered for standard LCD displays (having noticed the sibling comment about that). Change .png to .pdf if you would rather have the document from which it was rendered.