I had a copy of this guide during the two years I lived in Bcn and it proved to be invaluable!! I used it constantly during the first few months; not just to find my way round and learn about all the top sights, but also because it covers what you might need to do if you are moving there more permanently... It's a wealth of information!
Many of the places it recommends (restaurants, bars, clubs, etc) were often places that my Catalan friends went to anyway so I can assure you that Time Out doesn't always send you off to the main 'tourist' spots to be surrounded by other foreigners! However, the Bcn scene is always changing (every couple of months) so it is hard to always be up to date... even if you live there... so a guide book isn't going to be right all the time!
I like Time Out guides as they don't just give you the info you need to enjoy life at your destination as a local person would, but they are also stylish and easy to use.
I have used Time Out guides on all my urban travels and have never been disappointed. They are excellent! I've already got the Time Out guide to my next destination: San Francisco...