In that case, the Seagate SSHD will speed boot times substantially (probably more with W8 than W7) over a regular 7200 disk. Don't expect SSD speeds, but it will be significantly better than a traditional spinning disk at commonly used tasks and will get better as it "learns" your frequently accessed files. It reduced my boot time in a Windows 7 laptop from ~2.5 minutes to 25 seconds. For uncommonly used files or large copy speeds, it was slower than the 7200 RPM drive.
Seagate's laptop and desktop drives have had quite a few reliability issues as of late though...my SSHD laptop one was replaced 2 months in (fine now), and brother's desktop Barracuda is making noises after <1 year.
If you are looking for both reliability and speed...