I'm from Catalonia. So funny to read your post (Cantonese...

)
This TLD is very used here, there are more than 55.000 registered dotcat domains (for only 7M population). It is a cultural community TLD and the restrictions commented are true: no cats in the content and, at least must be in catalan language. This not mean that you can develop a multilingual site.
Otherwise, it has no much value. There is no market. Although the succes of registrations, the main TLD for companies is still dotcom.
I own mp3(.)cat, for example and have no offers at the moment.