For certain definitions of seamless. Windows has a habit of messing up nix file permissions and sometimes things just don't work at all unless you do it on the Windows side.
Windows default filesystem is NTFS and it's pretty safe to write. I certainly wouldn't set up something like a server which relies on this, but for personal use or even a development workstation I think it's fine.
I guess it might be a good idea to first check the disk using Windows after something like a power loss while the NTFS partition is mounted. But apparently NTFS-3G (one of the NTFS drivers) can also use the journal to recover the filesystem after a power loss.
