Fair Rated 3 out of 5 stars
The first time I tried to use this add-on it wouldn't work. I had to 'debug' my Firefox (look for conflicting extensions, disable them, look at my advanced settings, etc.) before it would do the trick. I'm guessing/hoping that was more of a problem on my end than an actual software bug.
Otherwise simple and easy to use.
In my opinion, Custom New Tab has a slight advantage over this add-on, just because it's restartless.
[Update]: looks like the site hosting the instructions is down.
Link to the archived copy: https://web.archive.org/web/20130523100545/http://www.grizzlyape.com/addons/any-new-tab/instructions/