At the USENIX File and Storage Technologies conference in February, researchers from Northeastern University (disclaimer — I'm one of them)
dissected shingled drive performance both figuratively and literally, using both micro-benchmarks and a window cut in the drive to uncover the secrets of Seagate's first line of publicly-available
TLDR: It's a pretty good desktop drive — with write cache enabled (the default for non-server setups) and an intermittent workload it performs quite well, handling bursts of random writes (up to a few tens of GB total) far faster than a conventional drive — but only if it has long powered-on idle periods for garbage collection. Reads and large writes run at about the same speed as on a conventional drive, and at $280 it costs less than a pair of decent 4TB drives. For heavily-loaded server applications, though, you might want to wait for the next generation.
Videos (in 16x slow motion) showing the drive in action — sequential read after deliberately fragmenting the drive, and a few thousand random writes.