Where aptX™ maxed out at a bit rate of 352kbps, aptX™ HD can manage 576kbps. It has better S/N ratio in the lower frequencies as well as lower latency - a big plus for synchronizing video and audio for HT wireless headphone users.
It is lossy, but promises better performance than the highest (320kbps) MP3 or AAC formats. It is however, not "better than CD" quality as stated in Qualcomm® literature and won't reach the quality of your wired BDx S/PDIF, AES/EBU, USB or HDMI wired connection.
I imagine for now it will only be available on a very limited number of select high-end phones and tablets.