We joined the Gaudí Tour a few days ago and it simply was amazing!
The meeting point was easy to find [ just watch out for the ladies in the "fancy green jackets" :-) ] and our guide Jessi was awesome!
She was passionate about Gaudí, very knowledgable, happy to answer all our questions (not only the ones concerning Gaudí) and knew how to make the tour interesting for everyone.
As you know time flies when you're having fun which is why we didn't even realize that we've been walking four about 2 1/2 hours.
Another benefit of this tour is that you don't have to pay the entrance fees of the bulidlings (well, you don't go inside) but still get an impression of the decorations because the guides show you some pictures.
So go for it - you won't regret it!More