I stumbled upon this by chance and saw a bunch of 1-star ratings, which inspired me to write my own review.
I’ve been using this extension for 6 years now. Pros:
- It quickly translates any text you can select, either by clicking with the mouse or using a keyboard shortcut
- Killer feature: It has seamless two-way language switching. For example, if you’re translating text from Russian to English but at some point need to translate it back, it’ll figure it out on its own and switch the translation direction! Neither Google Translate nor any other service has done this.
- It rarely freezes. Over the past 6 years, I can count no more than 7 days when it froze on its own.
Drawbacks (for beginners; once you know about them, they aren’t annoying):
- If the internet connection drops during a translation, it doesn’t display an error message — it either keeps spinning for a long time or just disappears.
- There’s no description on the homepage of such a cool feature as seamless language switching (see above). That’s their oversight.
That’s all.
To complement other reviews: Pro needed only if you seek for a some extended features. Extension never required payment for using free version. If you are seeing promotion to make it Pro after installation, you at the extension' settings tab, simply navigate to other panes to make appropriate to you settings and close the appeared tab.

Очень доволен, работает без сбоев

I really truly do love this translation app, it's easily the best one I own and have owned!!! :)

Le meilleur de tous les traducteurs en ligne (et j'ai essayé presque toutes les extensions de traduction automatique).

Je l'utilise généralement sur des sites de fanfictions : c'est pourquoi je donne un avis si dithyrambique. Rien, en effet, n'est aussi complexe que la traduction d'un récit.
Il est également très pratique de pouvoir voir dans une petite fenêtre la phrase originale : il suffit juste de passer sa souris juste au-dessus de la phrase en question.

Notez enfin que je ne me sers que de la version gratuite (non professionnelle).

one of the best!

türkçeden ingilizceye çevirisine güveniyorum.

Funktioniert sogar im mobilen Android Firefox. Sehr schnell. Danke!

Efficient, quick and simple translator. I have been using for about a year and never had an issue with translating or getting the program to work.

Highly recommend.