I am halfway through my Noom course.
It is expensive. Tbh I have found that helps me - if I'm putting my money down, then I'm going to give it a proper shot. I decided I needed to lose my lockdown weight. I joined in June. I had over 15 kgs (33lbs) to lose.
It's calorie counting basically. You get out what you put in.
Downsides for me:
Twee language, #hashtags #everywhere, occasional glib advice to "just snack on a cucumber!", nutritional advice which seems a bit like Weightwatchers in 1995, a rather sexist default setting of starting every single woman at 1200 calories regardless of height or activity level (the algorithm does do some tweaking for men based on these factors), the calorie counter in MFP is miles better (more foods in database, more portion size options).
Upsides:
There are tasks to complete every day and that keeps you thinking about it and helps you stay on track. (I wake before everyone else in my house so I do the Noom articles and quizzes then. That sets me up for the day.) The groups are quite good. Lots of shared articles; sometimes people contribute a bit of chat and often they don't. But that again draws you back to thinking about it. It helps to post your worries and someone will cheer you on or offer words of support.
In two months I have lost 8kg (17lbs), eating about 1600-1800 calories a day. I am combining that with exercise. Obviously I expect that speed to slow a bit as it gets closer to my goal, but I'm v fat so it goes quicker at the beginning. And I've signed up for four months so I can do it over a long enough time period that I can recover from a few hiccups/social events while still on the program. Like, last week I was totally fed up with life in general and I ordered Chinese food and a few beers. (Obviously I don't do this all the time but I was comfortable enough to know that by now I could pick myself up again the next day and it would be easy to recover momentum. I did and it was.)
I've even started to believe I'll make my goal weight, which I don't think I expected when I started. (You try not to be "negative", but it's just so hard to see it, isn't it?)