Best out there but isn't perfect Rated 4 out of 5 stars

compared with the following add-ons:
Webpage Screenshot in Firefox (♥♥♥♥♥)
Screengrab (fix version)
Abduction! - Webpage Screenshots Screen Capture

Pros:
I've found this to be the best of all.
No spammy advertisements that you cannot opt out of.
No restart.
Has both a toolbar button and a context menu item.
Good built in editor that opens in a new tab after capture.
Simple & easy to understand options.

Cons:
Upload feature cannot be customized. (only two options)
Cannot capture to clipboard.
No "open with..." button after saving a screencap.
No "Capture Region" feature.
"Discover Similar Sites" item is annoying with mis-clicks.

Please add more upload options. I personally have an account with imgur and prefer to upload there.

Sending screencaps directly to clipboard is useful for sending screencaps directly to an img editor of the user's choice. Either add this feature or add an "open with..." feature.

Capturing certain regions is possible if the extension can automatically select <div> sections similar to how adblock plus selectively blocks items. For an example of this, check out a certain screencap extension in chrome called "Screen Capture (by Google)"
link: https://chrome.google.com/webstore/detail/screen-capture-by-google/cpngackimfmofbokmjmljamhdncknpmg?hl=en

Please hide away the "Discover Similar Sites" button. I don't mind that it's there, just don't put it next to the "Capture Full Page" button. Maybe add a separator?

I also don't mind if you add a "Rate!" button hidden away in the options dialog or in the "annotate your screenshot" page along with the "share your love" buttons.

This review is for a previous version of the add-on (2.4.0.1-signed).