Works exceptionally well. If there is a cookie, it will be listed, and it can be allowed.
The only problem I have with it is that it does not have any UI for quickly-redirecting sites. This is happening more and more frequently that an array of sites bounce me in rapid succession from one to another, each requiring cookies, and this tool flashes on them but does not allow to stop and allow cookies. On such sites it has to be disabled completely, which totally defeats the purpose.
I still give it 5 stars because otherwise it does exceptionally well!

As far as I know this is the only extension that blocks cookies from the get go and allows control over third party cookies also.

99.99% of the time I have no issue with the extension - it works well.

There are some sites though that this does not work with such as TomTom Routes/MyDrive and just today usps.com. USPS informed delivery worked flawlessly till today.

Edit - I went through the USPS website and looked for pages where there may be a cookie not seen on the informed delivery pages - I found it www.usps.com - did not show on the informed delivery page but was never the less necessary and back to business with that site. Still no luck with TomTom though I know its there somewhere!

Moved the ext to 5 stars.

Would still love to see a general exception on a site by site basis but having USPS back without having to disable the ext is a relief.

I've been using this extension since the legacy ones stopped working and I only had one problem today logging into my router. So, that's a few years of perfect performance. I wanted an extension that would let me allow/block cookies on a per-domain basis, including third party cookies and would remember my choices between sessions. I imagine this is what most regular users need, just a simple and effective cookie control. I don't see any other extension out there that does that. If you need developer's tool look elsewhere, and read the description before installing. For users that want to clear the cookies already set, just use the Clear Recent History option. Overall, I am extremely grateful for the effort that Craig Miskell is putting in the development of this extension and I'm going to submit a suggestion for it to become recommended. I hope this draws more people to take a look at it. Thank you, sir.

Seit Jahren suche ich einen Ersatz für mein gutes, altes Cookie-Monster. Stunden verbrachte ich damit, ein ähnliches Add-On zu suchen. Endlich! Jemand hat es nachprogrammiert. Ganz lieben Dank Craig!
Craig antwortet sogar auf Anfragen und zu meiner großen Freude ist geplant, eine Backup-Möglichkeit ebenso einzubauen, wie ein Auto-Import der erlaubten Cookies aus FF. Ich freue mich darauf!

translated to English:
Since years I search for an replace for my good old "Cookie-Monster". I spent hours in searching something like it. Finally: Somebody programmed a copy-add-on of its funktions. Many Thankys, Craig! Craig answers even to mails. To my excitement it is planned, to add a backup-solution as well as an auto-import of the cookie settings. I am excited about!

Great! Now all it needs is to show status on the button.

if you want to control who can write cookies to your machine, this is the extension to use - fantastic!

amazing !!!

I echo other reviewers where they mention that this addon allows DEFAULT BLOCK (with exceptions) for cookies. No other addon gives us back cookie control like this. THANK YOU Craig Miskell.

Some features which I hope get added soon :)
1. The cookie toggles do not show up when browsing in Private mode. Please fix that if possible.
2. Possible to extend this addon to Firefox for Android? I would love to be protected across my devices!

This is as close as we're going to get to something that even closely resembles the old "ask me every time" option for cookies in that it will actually block cookies from being set for denied websites and the whitelist/blacklist stays between sessions. Other cookie managers still allow "blocked" cookies to be set on your computer, only deleting them after a period of time or the session closes, CookieMaster does what it's supposed to and it's super simple. I do wish I could set some websites to only set cookies for a session instead of just allow/block, but I'm totally happy with the way this is right now.