dpkg -i is more like rpm in this respect - it'll only install from the file(s) you specify. Unlike apt-get, which will resolve dependency issues and download the required additional packages as needed.
On the other hand, dpkg -i will not refuse to install entirely (unlike rpm), it'll half-install a package with missing dependencies, so that later apt-get commands that happens to install the missing dependencies will finalize what dpkg -i started. If the dependencies could be resolved by on-line packages, that is. Otherwise it's package hunting and more dpkg -i.

I hope that made sense..