As humans we all have the tendency to compare ourselves to others in various ways. Whether it's looks, jobs, relationships, whatever. So when photographer's, artists and hobbyists ask me for advice I always say this: "Never mind what everyone else is doing. Concentrate on you."
There is nothing worse than comparing your work to the work of others, especially those who you believe are superior. There is also no point in it. If I compared my work to my favorite photographer (Richard Avedon), I may as well quit the business all together. I would never feel my work was good enough.
So, instead of comparing your work to others, compare your work to your own. Find those images from your first few photo shoots and compare them to your latest. If you think your work has improved, good for you! If not, keep working at it! Keep in mind this is more for those who have some shooting time under their belts.
When I occasionally feel like crap about my work, I look back at my early images and breathe a sigh of relief that I have at least improved over time.
Above are examples of my work from 2006 and 2010. The 2006 image was taken a couple of weeks after I got my first camera. Embarrassing. Everything about the image is terrible, not just technically, but look at the styling! All done by yours truly. I literally asked a girl I knew from high school to let me practice by taking her photos at a near by park. This shot is beyond cheesy.. and terrible.
The 2010 image was taken of a local model who I adore and is one of my favorite models that I've worked with. This image was taken in a small condo I used to live in. The living room to be exact. I used one studio light (with a soft box) behind a white sheet and a reflector. Oh how I love simplicity. Even though the set-up sounds lame, the outcome is exactly as I wanted it to be.
It's time to stop beating yourself up over the fact that so-and-so does better images than you. Work towards creating photos that represent you and your own style. Create something you can be proud of.