I believe one of my hesitations has also been trying to figure out if I want the program to allow me to update the task and show progress bars. But ultimately I keep concluding that such a feature would just complicate what I was trying to do. Really just need to have an easily accessible location for the things I need to get done, sorted by topics I set up. Your application does that.
I really liked your program because it was straightforward and easy to use. Control-Enter to move a list to accomplished was nice. I also like the ability to move them up and down with the keyboard, though a chrome extension I have running has taken over the control-down-arrow. I did also notice the ability to create empty lines. At first, somewhat embarrassingly now, I wasn't sure if each time I pressed enter made a new task entry or if it was a line in another task. After a few seconds I figured it out, though. Just tested it out on my iphone and worked great. For desktop, I was a little bit annoyed as well that I had to drag from the icon, but that wouldn't be a consideration truly if my control-down-arrow wasn't already hijacked. On my phone, the arranging them was easy.
Personally, I could read everything well on my screen. But I could see how this might be a problem for many others and the ability to change the colors/sizes might be a great feature. Honestly, though, I don't know if I would change those settings, myself. I'd probably just stay with what the default was set to (but I usually go with default settings on almost everything).
I didn't go to sign up so I can't speak about that experience. Why am I hesitant to not just throw away the two commercial options and go with yours for free? It being free may be one of the reasons. I'm not sure. I feel like my list is very personal and I want to know that it is secure. Your product honestly showed me everything I kind of would have wanted from the program I was looking for. I liked the about page with the story of your developing it. And honestly I don't know where you plan to go with this, which might be where my hesitation resides. I don't know if you're wanting to gain users or not. Is this something you might take down in a few months? Something addressing those concerns, and maybe "social proof" showing me that others are using it and it's going to stay around would probably have secured your product as my choice.
Don't know where you want to go with your product, so I hope my ramblings have helped. Feel free to ask any questions.