My sailboat has Bermuda sloop rigging at the moment. Its sail plan looks like this:

As opposed to sloop, junk rig looks like this:

There are pros and cons to each of these rigs. Basically the single one con of junk rig is that it cannot go into the wind as close as the sloop. In meantime, there are a number of pros in favor:

• easy handling
• auto tacking
• simple reffing (just ease the halyard)
• low pressure on the sail, therefore it can be made of cheaper matterial
• there are no stays, so nothing to get in the way while moving around aboard
• there are no jibs to store, handle and to switch when wind picks up
• the mast is more to the front so there is more space in the cockpit and nothing to bump head into
• less rigging and hardware needed, meaning lower cost
• mast is cheap (2mm thick aluminum pole will do)
• it looks good

For more details of a junk rig see the 3D models below:

Animation of reefing with a junk rigged boat