Vajra B. Hairava
I'm torn at the moment between Portuguese and Catalan. They're both pwettyfull, though Portuguese has extreme usefulness going for it.
Teach yourself Catalan
The fact that you are planning to use this book most probably means that you already have an interest in or curiosity about Catalan.
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Of a population of almost 11 million people some 6 million have Catalan as their native tongue, which a further 3 million can understand and potentially use the language.
Obviously there aren't many who speak it, let alone learn it. But it is useful if you go to Barcelona to the French border.
Don't learn a language for it's usefulness, learn it if you have an interest in it.