This hosting image isn't really good because sometime when you upload to this forum, the image will become tiny and when you want to set it bigger, the image would be blur.
You are not using it correctly. It's not their fault LOL. I use it sometimes when imgur does not load or have any temporary problem. The only reason I do not use it always is because of more navigation required than imgur. On imgur you only click upload and then right click for the image link. But in imgbb you need few more clicks to get the image url.
It's been down/not working for the majority of the day, and it's a really useful tool for adding pictures to my posts using BBcode.
Sometimes your ISP can block the URL. Try to use VPN. It works fine.