From JargonFile:GoodThing:

1. Self-evidently wonderful to anyone in a position to notice: "A language that manages dynamic memory automatically for you is a Good Thing." 2. Something that can't possibly have any ill side-effects and may save considerable grief later: "Removing the self-modifying code from that shared library would be a Good Thing." 3. When said of software tools or libraries, as in "YACC is a Good Thing", specifically connotes that the thing has drastically reduced a programmer's work load.