I've installed DBD::Oracle on Solaris several times before. You will need to reinstall DBD::Oracle with the appropriate files. You will want to look at DBD::Oracle and Oracle 9i standard client install for more information on how to do a minimal install of Oracle in order to get DBD::Oracle to compile successfully.
My criteria for good software:
Does it work?
Can someone else come in, make a change, and be reasonably certain no bugs were introduced?