I really love this tool! Is perfect when i do a marathon.
You can decide to choose if you want to increase timer with donations or subs, and this is nice because a lot of people want to support you!
There are a lot of clock's customization too, and so you can decide animation when someone follow/donate/sub and you can change colors, background animation and a lot of more feature!
It's so complete and the creator is really a good guy, he helps you if you have a problem and he's always open to new ideas and suggestions!
I like it, I use for other streaming besides Twitch so I haven't tried all it's features. Only issues are that I've had troubles figuring out exactly what some things do, but with trial and error it's not too difficult. Also there is a delay between the site and the timer url and can be frustrating if you're wanting it to update faster.