A good list, but I just have to add one which is a killer for any good app:
PHP has terrible unicode support. Almost uniformly every app that starts out using the default PHP function set ends up failing horribly when data with non-european (or even just non-ascii) characters end up in it. There are a whole lot of kludge workarounds, but they're basically an admission of defeat rather than a real statement of support.
PHP has terrible unicode support. Almost uniformly every app that starts out using the default PHP function set ends up failing horribly when data with non-european (or even just non-ascii) characters end up in it. There are a whole lot of kludge workarounds, but they're basically an admission of defeat rather than a real statement of support.