Gearscore has infected Destromath. First running rampant on the horde side, people have begun to treat it as the gospel on alliance side too.
This is my opinion on gearscore. It should be thrown in a sack. The sack should then be thrown into a river, and the river hurled into the sun. The idea of rejecting people based on what is essentially a summation of their item levels is moronic, given the amount of data it doesn't include. The whole notion of the addon is to cause people to forgo actually looking at someones spec and gear. Which is why it fails. It's an abacus, not an audit.
However, the concept of an addon which does the work of inspecting a players gear is not without merit. Sites such as Wow-Heroes and Be.Imba.Hu have been doing so successfully for years, and without the flaws of Gearscore. This is because they run a full audit which takes into account specs, gems, and enchants. The DK with spellpower gear is properly called out for being a tool, not rewarded with a bigger e-peen to flex.
There is an addon that does this correctly. It is new, and it will hopefully displace gearscore. It is Elitist Group. What elitist group does is present a rudimentary audit to any player who is in your group. This is most effective in the LFD pugs. Upon opening the summary screen, you're presented with a panel that shows you each item they're equipped with, their item level, gems and enchants, and if each is appropriate for their spec. It also points out if they're missing any talent points, and how much of each teir of content they've cleared. At the end of a five man, or on command in a raid, a window comes up that allows you to rate a player 1-5, and write a short note about them. These can be shared with other players running the addon, creating a kind of reputation system.
The system is not perfect. It flagged me for using the 30 stam to shoulders PvP enchant. However, it's leaps and bounds better than gearscore, and something that I'm not afraid to endorse.