For the past several years Seagate has held a strict timeline for releasing updates to existing product lines. With each update more performance was achieved and less power consumed by the product. The Constellation Series is the higher capacity, lower performance product in the Seagate enterprise line-up. The Savvio (10K RPM) and Cheetah (15K RPM) being the higher performance products of the enterprise line. With the new platter density, the Constellation is actually approaching the same levels of performance of the Savvio.
When looking at the previous generation Constellation, we can see just how much has changed in a year. The new Constellation.2 is quite a bit faster than the first generation drive and even doubles the available capacity. It has been quite a while since we've seen a true doubling of capacity in a single year, but the 2.5" form factor enterprise market has really caught on and manufacturers are looking to produce 2.5" drives with nearly the same capacity as their 3.5" counterparts.
When it comes to pricing, there is still a premium paid for the 2.5" form factor in the original purchase price, but the smaller drives consume less power and over time the additional cost is absorbed by the lower power bill. Another price premium is added when choosing the SAS option, but that is now down to less than 20 USD per drive in the retail market.
The Seagate Constellation.2 1TB SAS HDD is currently available for 243.31 USD. This price is higher than a consumer level drive, but you gain enterprise features and build quality. There aren't very many 1TB 2.5" drives available on the market to begin with, but the Seagate Constellation.2 is the first with this level of features.