Anandtech posted a review on the Micron P320h PCIe SSD (700GB)

Well over a year ago Micron announced something unique in a sea of PCIe SSDs that were otherwise nothing more than SATA drives in RAID on a PCIe card. The drive Micron announced was the P320h, featuring a custom ASIC and a native PCIe interface. The vast majority of PCIe SSDs we've looked at thus far feature multiple SATA/SAS SSD controllers with their associated NAND behind a SATA/SAS RAID controller on a PCIe card. These PCIe SSDs basically deliver the performance of a multi-drive SSD RAID-0 on a single card instead of requiring multiple 2.5" bays. There's decent interest in these types of PCIe SSDs simply because of the form factor advantage as many servers these days have moved to slimmer form factors (1U/2U) that don't have all that many 2.5" drive bays. Long term however, this SATA/SAS RAID on a PCIe card SSD solution is clunky at best. Ideally you'd want a native PCIe controller that could talk directly to the NAND, rather than going through an unnecessary layer of abstraction. That's exactly what Micron's P320h promised. Today, we have a review of that very drive.

  Micron P320h PCIe SSD (700GB) Review: The First NVMe SSD