Works well, fast. The icon that sits next to the URL bar is exactly the same than this addon icon, that you can see on this page.
But there's no icon customization and I prefer the Close Tab Context Menu addon, that does exactly the same, but with a darker icon, it's more visible (on default theme or clear theme) . So, if you have a clear theme or the default theme, rather use Close tab context menu, and if you have a dark theme, Close Current Tab is better.

With these 2 addons, you have everything you need, clear cross or dark cross, as none has icon customization that fits to the user theme. (But I still prefer bigger, dark, black cross).

Suggestion: adding undo close.

would be great if i can place the button somewhere else too.