Sony revealed at Gamescom today that people who buy the PS4 console will receive a free 14 day trial of Playstation Plus.
This trial will let you use Playstation Plus to get there Free Playstation Plus games, so it looks like you have full access to Playstation Plus with this trial and are not limited with access.
But note that with Playstation Plus, when you're 14 days trial are done, you can no longer play them free games that you need Playstation Plus for, you will need to buy Playstation Plus to play them free games again.
This trial will let you use Playstation Plus to get there Free Playstation Plus games, so it looks like you have full access to Playstation Plus with this trial and are not limited with access.
But note that with Playstation Plus, when you're 14 days trial are done, you can no longer play them free games that you need Playstation Plus for, you will need to buy Playstation Plus to play them free games again.