cocoAspell does not work with Pages. Pages ignores the language specified in the Spelling window and uses the language settings from the "More" tab in the Inspector panel. In my opinion this is a gross inconsistency with the normal user interface experience. The conclusion is that you can use cocoAspell with Pages if you are lucky to be using one of the Apple defined languages.

Dictionaries created for aspell version 0.5 and above will not compile with cocoAspell version below 2.0.

New in 1.1. Language (dictionary) names are now displayed in the default system locale. The OS identifies spelling dictionaries by their names. It means that switching system locales will effectively disable all dictionaries. So, after you change your system language you should restart System Preferences, open Spelling panel and enable the dictionaries. Note that the preference settings for individual dictionaries are preserved.

If "Check spelling as you type" (on-line spell checking) is enabled, cocoAspell marks TeX commands as misspelled words.

This is a problem of how the text is served to a spell server. With on-line spell checking enabled Cocoa text widget sends the words to the spell server (cocoAspell) individually. For example, cocoAspell receives "documentclass" instead of "\documentclass" or (what would be even better) "\documentclass{article}". It has no ability to distinguish between regular words and TeX commands.

Note that spell checking works as expected if you use the global "Check Spelling" command.

I am currently looking for a solution to this problem.

Enabling/disabling spelling dictionaries using an older version (prior to 1.4) requires a re-login: you have to log out and log in back into the system for the changes to take effect. It seems that the spelling services cannot be registered with the system dynamically (the menu in the "Spelling" window will not update). I am not sure whether it is a bug or a feature. I hope it is a bug and Apple will fix that soon.

Combining multiple filters is strongly discouraged. A combination of the URL filter and any other filter should be OK. However, cocoAspell may get very confused if you enable both HTML and TeX filters. This situation may change in the next release.

cocoAspell before version 1.4 will not start automatically when you login (as a service provider application is supposed to do). This is yet another system bug. You must add cocoAspell.service to your "Login Items" in the "Login" system preferences.

In some rare case the first time you spell check a document, cocoAspell may fail to come up with a list of suggestions. It happens because the spell server needs some time to load the dictionary and initialize itself. The client application simply times out on the spell checking request and behaves as there were no suggestions. This may not happen at all if you have a fast machine.

Building a dictionary may fail if the full path to cocoAspell contains space characters. That will happen only if cocoAspell is installed in your own "~/Library/Services/" and the name of your home folder contains a space.

There will be some problems with German and Portuguese dictionaries installed on a UFS partition. If you put one of these dictionaries on a UFS partition you have to manually create soft links to all de_CH, de_DE, pt_BR, pt_PT files. Each link must have the same file name as the original file in lower case. For example, you have to create de_ch.multi that points to de_CH.multi. This is a problem with the current version Aspell: it requires all dictionaries have names in lower case. This is not a problem for an HFS partition because HFS is a case-preserving system. UFS on the other hand is case-sensitive, so Aspell will fail to locate the files. Adding the links will allow Aspell to handle this on a UFS partition. This problem should be fixed in the next version of Aspell.