Rated 1 out of 5 stars

Have been trying to find out which one of my scripts has been causing memory leaks. FF memory usage would shoot up to 1 GB in no time, coupled with frequent 'Not responding...' and crashes. After hours of testing, narrowed the problem to Greasemonkey. Came here, looking for support, and noticed several people reporting the same. These latest versions are definitely not fit for public usage.
As pointed out by others too, 2.3 works fine.

Rated 2 out of 5 stars

version 3.1, 3.2beta1 and the whole 3.x series:
all have extremly memory leak and causing laggy performance. It seems like memory wont get released.

So go back to 2.3, this work.

Latest updates are broken Rated 2 out of 5 stars

RAM usage goes completely out of control. I've seen few times 2.5GB+ being eaten by firefox. Please fix it soon until then this addon is unusable!

Rated 5 out of 5 stars

Thx! Разработчики вас не забудут!

Rated 5 out of 5 stars

Many scripts don't work in Firefox 37.0.2, are greasemonkey incompatible?

Very mixed Rated 2 out of 5 stars

In theory this addon will improve your web browsing habits and life in general by 76% but in practise, things are quite different. Depending on which scripts you use, your internet can be absolutely crippled to a snails pace. 'Not responding' and other delays will become the norm.

This opens up another question on whether the scripts or addon are to blame but in order to find the culprit, be prepared to spend many hours working out which is at fault and many more editing scripts to exclude/include domains in order to ease the load.

I've also noticed huge memory leaks when GM is enabled. Within minutes, FF is using well over 1gb of RAM which isn't good.

This user has a previous review of this add-on.

love it ♥ Rated 5 out of 5 stars

One of the most powerful addon you can get. There are thousands of scripts you can install and customize your firefox how you like it.

This user has a previous review of this add-on.

Rated 5 out of 5 stars

Fantastic for managing your scripts
Just be careful of what you add.

A lovely add-on that packs a PUNCH when used right. Rated 5 out of 5 stars

As of version 3.0, all my complaints have been fixed.

First thing to mention - to get it out of the way - is that the quality of the scripts range from fantastic to horrid. The scripts shouldn't be taken into consideration here in this review though, only the program itself.

The program itself is fantastic. It runs the scripts perfectly, auto-upates them, and also provides a clear-cut GUI that makes it easy to do whatever you need to do concerning userscripts.

When coupled with high-grade, reputable scripts, this program becomes one that I put right alongside 'Adblock Edge', 'Ghostery', and 'The Fox, Only Better'.

5 out of 5 stars!

This review is for a previous version of the add-on (3.0). 

A must have! Rated 5 out of 5 stars

Very handy add-on. Couldn't do without it! :)

This review is for a previous version of the add-on (3.0). 

invalid, do not work the "Super Next Page" Rated 4 out of 5 stars

after updated 3.0, the "Super Next Page" script does not working.
"Super Next Page" is great excellent ! no substitute in similar as yet.
so...had no choice but returned to 1.15.

This review is for a previous version of the add-on (3.0). 

Greasemonkey 3.0 gives you a new LIFE & HOPE xD Rated 5 out of 5 stars

"Multi process Firefox compatibility." is a next generation of Greasemonkey

This review is for a previous version of the add-on (3.0).  This user has a previous review of this add-on.

神器之一 Rated 5 out of 5 stars

one of the greatest addon for firefox big fan

This review is for a previous version of the add-on (3.0). 

Wrong link Rated 5 out of 5 stars

Great addon, but the "Add to firefox" button at the top installs an old version!

This review is for a previous version of the add-on (2.3). 

Rated 5 out of 5 stars

Working flawlessly for me!

This review is for a previous version of the add-on (2.3). 

Rated 5 out of 5 stars

Great addon! I'd like to see it available for Android, though.

This review is for a previous version of the add-on (2.3). 

Rated 5 out of 5 stars

This is a great extension that lets me make little scripts to fiddle with the way sites I frequently use work the way I want. Great functionality, and great firefox integration.

This review is for a previous version of the add-on (2.3). 

Rated 4 out of 5 stars

Works great so far, but lacking so many features from its Chrome's counterpart (tampermonkey).

This review is for a previous version of the add-on (2.3). 

Rated 3 out of 5 stars

C'est un addon très utile pour personnaliser Firefox malheureusement il n'est plus assez perfectionné si on le compare à son équivalent pour Chrome (tampermonckey). Donc très utile mais plus assez moderne.

This review is for a previous version of the add-on (2.3). 

Rated 4 out of 5 stars

This is absolutely not abandonware (points to the review below). If you look at bugzilla reports and the github, the Greasemonkey people are very active, including working toward e10 compatibility.

With that said, this is the go addon to use scripts. It works well for most part, but in my opinion the functionality of the addon itself is falling behind its Chrome's counterpart (tampermonkey).

This review is for a previous version of the add-on (2.3).