PAOLO TRAMANNONI  I try sometimes to use the French version on a G5 with Tiger. It's hard to say the program is usable. It is extremely slow. If it finds a foreign word, it takes forever with the spinning ball on the screen. And after each change, the check returns to the beginning, even if you try to move the cursor in a different part of the screen.

The program has never seen improvements during the years (I use it since the times of OS9). And the developers are very proud of how it works. So, I doubt there will be any improvement in the future.

As a grammar help, it could have been useful, since I see it gives good suggestions most of the time. But they should find a different software developer.  
(Version 7.1)

GREGMC  I have Grammatica and Grammarian by Linguisoft. I purchased Grammatica because I wanted a grammar checker that worked as a separate app; Grammarian works via the input source menu, which on occasion causes minor system clashes.

On the whole, Grammatica works well for spelling, however, checking grammar simply doesn't work. It fails to correct my "it's" when I should type "its" (and vice versa) and doesn't have a clue about the use of commas, colons, or semicolons. If you want it to pick up on a dangling preposition or whether a sentence is in a passive voice, forget it.

Grammarian by Linguisoft is a much better grammar checker that, despite its quirks, I use daily. Grammatica, unfortunately, simply doesn't compare. Looking at the preferences panes for both apps makes the difference clear: Grammatica has a very simple preference pane, with no options for customising how it checks (or doesn't check!) your writing. Grammarian's preference pane has hundreds of options, a complete set of rules on grammar which the user can customise for his/her own use.

In short: Grammarian, a copy of The Elements of Style by William Strunk & E.B. White, the Oxford English Dictionary, and the Oxford Thesaurus, and you're covered.  
(Version 7.0)

NEIL2112  Starting with the simple, I tried it out with 'Hello my name am Bob.' It identified the word 'Hello' as a problem. Next, 'Me don't liked fishings.' This sentence checks out just fine. This software simply does not work as advertised. Not going to rate it though so the developer can address this assessment.  
(Version 6.2)