It is no longer free, there is now an admission fee to the 'monumental area' which includes the most important places you'd want to see. once you buy the ticket, you only get admitted in a short window of time (30 min) but you can stay as long as you like once you are there.
Bummer. There is another entrance. But, I'm sure they have a troll booth there as well. You take the No 24 bus from the main city area up to the Parc Guell stop. Have the driver call it out. You walk across the street and you're in the parc. There's a small historic Gaudi house on your left as you walk into the park. The main monument things are farther into the parc. The bus is much easier than the metro. The metro stops don't get you that close and it's all uphill from the metro stop. A lot of uphill. Here's the routing for the No 24 bus. http://www.tmb.cat/ca/c/document_library/get_file?uuid=4ff9da83-eb9a-4498-a77d-99c1ff9b7366&groupId=10168