Greta is a really great tool. I used it to build a prompt and snippet manager, which I run locally on my PC. I use level 3 with 1,500 credits.
I needed about 640 credits for the tool. To build the tool, I created a simple checklist in an Excel spreadsheet where I could record and check each step.
While building it, I naturally thought of more and more things that I could integrate.
Some things weren't implemented right away or were even removed again, but that's not a problem because I was able to check and correct these things at any time thanks to my structured checklist. This project took me about three days.
I used several LLMs to find out which one was best suited for this project. I settled on Claude 4.5. I estimate that at level 3 with 1,500 credits, I can create about two to three more extensive tools per month. That's perfectly sufficient for me. Roughly estimated, I would say that the credits are enough for about nine days of creating things. By that, I don't mean nine days of two hours each, but really nine full days, since testing the program always takes some time. If I build mini-programs without any bells and whistles, i.e., small, simple calculation tools, then I'm done in 10 to 30 minutes. I could build a whole lot of those.

Conclusion:
I used to build small programs with ChatGPT & Co. and it took me much longer. Greta saved me an incredible amount of time. With this tool, non-programmers can build things that would never have been possible before. However, if you want to create very large programs, you need to know that even programmers have to split up into teams and also need longer to create something big.
For that, I give it a full 10 tacos.