The new Lightroom 6 has face recognition, Panorama Merge (stitch together multiple images, including RAW files to create unique panorama shots), faster performance for importing and perfecting your photos, Advanced Video Slideshows and more.
You can order Adobe Lightroom 6 for Mac and Windows from Amazon, B&H Photo or Adorama.
For a comparison sheet with Lightroom 4 and 5 and detailed information on the new product, see files provided by Adobe here.