30DS seems to do nothing

I did 30DS and didn't lose weight from it, but I did get the benefits of increased endurance, overall improvement in my fitness level, and muscle toning. It's only a 27 minute workout, so you might need a longer workout or try combining it with some other exercise for variety. Also, I'm never one of those people that saw immediate results when doing new workouts. 10 days, I wish! For me it takes at least 3-4 weeks for my body/metabolism to figure out that I'm doing something different.

I'm done with level 1 of the 30 Day Shred and.... nothing has changed. I haven't lost weight despite restricting calories, my measurements haven't changed, and I barely notice a difference in endurance or fitness.
I wonder if it's even worth starting lvl 2 if I'm not gonna see results

It depends on how fit you already are, it might be that level 1 is too easy for you to see any changes in your physique or endurance. The 30DS was the video that kickstarted my fitness and weight loss a few years ago. I DID see significant change in my body and endurance after a week or two, but I was VERY out of shape at that time. I also did not follow the 30 days part of the program, I worked out every other day, so it took me 2 months to finish. However, at the end, I had lost 15 pounds and many inches. I also visibly gained muscle in my legs, abs, and arms, enough that people started commenting on how buff I looked.

I still do the 30DS when I am crunched for time and want to get a quick workout in, or when I'm feeling tired and want an easier workout. My endurance and fitness level now mean that most of the moves are easy and I can used heavier weights as well as move faster to up the intensity if I want.

If you are not in shape, it might be that you aren't working hard enough to see a significant change yet. It might take you much longer to work up to the level of endurance and exertion that will shape your body. If you are not going through the movements as quickly as Jillian's "girls" in the video, you aren't getting all that you could from the workout. Also, if you are doing all the moves modified you aren't getting as much of a workout yet. It also might be that you are not eating the right amount of calories to lose doing just 20 minutes of exercise a day.