Is it good to use Ad Block Plus Firefox Add-on

As per the visitor's points of view, it is good because:

1. Page takes less loading time.

2. It improves the readability of the content.

But, for a blogger, it is not a good thing because, he/she losses ad views/clicks (money) due to Ad Blocker plugins.

It is really a good choice to block the ads displayed on a webpage to you on your operating system as it will then help the webpage to load in less time as it takes to load when it needs to display the ads. It also improves the layout of a webpage, like it looks more better without the ads displayed on it, the content appears to be more clear to us in comparison to when it appears with lots of ads on it. Even I sometimes block the ads displayed on my web browser.

Adblocker plugin often passes some of the sponsored ads. In such cases those adblocker plugins are not helping you in any way. So your only option is to disable them for certain websites as it hardly has an effect. For example, Youtube Ads are often filtered by adblocker, so disable adblocker for youtube. For bloggers, this plugin has made many blogs shut down their hosting because they didn't made much revenue from it. So I think adblocker on some sites is good but not for all. It is upto you to either support the blogger or avoid making them money. Depending on your choice you decide what should be done.

It completely depends on you whether you like to use the Ad Blocker or not. Since, earning from the Adsense is very difficult, there are many struggle for the approval of the adsense. If you see those struggle, you may not use Add blocker. I would prefer not to use those ad Blocker.

I do not really understand the question from exact point of view. Well, yes - the plug in is indeed a bane to the bloggers. But, then where is the question of installing or not installing come from a blogers point of view. You cannot stop a user from using the plugin.
In fact, ever since these ad blocking plugins have been popular, it has adversely affected most of the bloggers. On a personal front, I would not support using the plugin.