I think gel and shellac are pretty much the same thing, and I *love* shellac nail polish. I used to get shellac manicures done exclusively at the salon, by a really talented and efficient nail tech. The color would last for more than two weeks; I would have to get my nails redone only because they grew out too much...not because of chipping or fading. And with all the special effects that can be done with "additives," now...well there really isn't any regular nail polish color that can't be pretty much duplicated with shellac.
I ended up getting a bunch of CND shellac polishes and the UV light for home. I am glad I made the investment, but the truth is I am not nearly as good as my nail tech at giving myself a shellac manicure. The color gets too much on my skin, and it is awkward to try and remove it from the skin. I also end up being able to kind of peel the paint off my nails, when I do shellac myself. I think it's because I paint the layers on too thick, and for some reason it is difficult for me to paint thinner layers. So, while the at-home system is cost-efficient, the results aren't nearly as nice as what can be done by the right nail artist. Another downside to shellac is that the color needs to be soaked and scraped off, which isn't the most pleasant activity.
However, if a nail tech or any other person has the right amount of skill and practice, then shellac is SO worth it. The pros far outweigh the cons, in my opinion. I used to think I would *never* go back to regular nail polish, until I decided the salon visits were a tad expensive to keep up on, consistently. But it is just so nice to have nail color that doesn't go anywhere. It's resistant to nics, chips, and fading, and there is no drying time, because the UV light "cures" the paint. I also personally think shellac nails look spectacular.