Benefits

• Very easy to install/remove/upgrade. Only two files are involved, no registry modifications, and if placed in a directory that's already in the path, then nothing more than two files is needed.
• Starts up faster than standard gvim (especially no blinking!).
• Despite being less capable than a fully-installed gvim, is still more capable than most vi's, and takes only 50% more memory than notepad (3mb vs 2mb on startup).

Downsides

• No menus, no syntax hilighting, some other nicities not available (since the runtime files are missing)
• vimrc file could possible become difficult to upmerge to new releases if many pieces of runtime files are embedded, though I haven't found this to be the remotest problem yet.

Hints

• clipboard interaction:
  • middle-click pastes from the system clipboard
  • the * register represents the system clipboard. So the following notepad-equivalencies should be pretty straightforward:

    Ctrl-C (copy)  =    "*y
    Ctrl-X (cut)   =    "*d
    Ctrl-P (paste) =    "*p