The Seagate Seven made headlines for one thing and one thing only; its thickness. It has a gorgeous design, which does no harm, and other vendors should seek inspiration from the way Seagate packaged the product, as well as the cable design that came with it.
The Seagate Seven offers relatively poor value for money. It is expensive, and at 500GB doesn't offer enough capacity especially compared to the competition. It is squeezed at the lower-end by cheaper hard disk drives and by SSDs at the upper-end of the market. It's also a shame that it comes with a mere two-year warranty.
The Seagate Seven is a powerful statement of what Seagate's R&D can achieve. I don't expect it to span an entire portfolio given that the drive would lose its main appeal (the slim nature) if it goes to a two platter model. If you're after a hard disk drive that looks different from others, then go for it. Otherwise, look elsewhere, either in the classic spinning disk market or in the SSD arena. The super-sleek and way thinner Samsung T1 is also an intriguing option and one can expect SSD vendors to arrive with similar solutions over the course of 2015.