Having shot RAW-only, RAW+JPG and JPG only, I personally don't find that the kind of pictures I like to create, get any "better" for me by using RAW files - but it does take significantly longer to process RAW files.
So, I shoot JPGs happily.
The JPEG standard is a compression algorithm and some image-information will be lost when compressing. However, the extent and how noticeable it is, varies with the image.
I would encourage anyone/everyone to shoot RAW + JPG for several sessions to determine for themselves, if it appears to make any real or even important difference. Shoot your favorite types of images in your preferred type of light and post-process the RAW and the JPG file separately. Print both in 18X12-inch or more and do the comparison.
Just pick the very best of your shots and do it with and then decide.
Do your very best with both versions and compare.
Not every image is "better" because of the potential for more detail or dynamic range - but some certainly can be. It all depends on what you want from your images.
Although I disagree with Razvan about the stupidity of the arguments about size and convenience, I agree with the crazy-hair-guy's notion about: why spend money on all this great equipment and not get the "best" out of them. Which is why I think the best way is to make your own decision, based on a comparison of your results.
....ultimately it is completely irrelevant how you arrived at the end-result - all that matters is if you like your images or not...whether you used a cell-phone camera, $100 Lensbaby optics or even JPGs to produce it...