Upon pulling up the Puggable.com page, there's no homepage or sign-in -- you simply get a prompt for your geographic location, realm, and character name, and that appears to log you in to the service. After doing so, you get another popup, and here lies the problem: the page asks you install a plugin from Vivox. This plugin is how the whole thing works -- it hooks up to your mic and speakers and allows your browser to work as a voice chat client (rather than a dedicated app like Ventrilo, which most players are currently using already). However, installation of any browser plugin is clumsy, first and foremost because they're one of the main ways hackers and spammers can cause trouble. So it's likely that if you do try to install Vivox's plugin in Firefox, you'll get a warning, which Vivox then says you should ignore, and install the app anyway. You must do so to actually use the service.
In Vivox's defense, as long as you follow their instructions, the plugin will install easily and quickly. As major browser addons go, they did this about as well as they could (and of course the plugin is not harmful at all, and won't cause your account to be hacked). But especially with the WoW audience already on guard against third-party installations and software, this will likely be a hard sell for the players joining a random PuG who have never heard of this service.
From there, you move on to the main Puggable page -- your character is listed along with any other characters that are in your "PUG"/chatroom, and there's also options to set the instance or boss that you're working on (along with dynamic links to a number of WoW databases and other resources). Up in the top left corner, there's a link that says "Share this PUG," and that's where the crux of the system's benefit comes in: You can simply give other players a URL for them to plug into their browser, and as long as they have the Puggable plugin installed, they will join your chat immediately. No sharing Vent IPs or passwords, no multiple Vent servers to deal with, just put the URL in and go.
In practice, it might not be that easy -- I got it working on two different computers, though our own Alex Ziebart had trouble getting the browser plugin to recognize his sound (as you can see in the gallery, there's a window to choose a sound source, but if your mic isn't recognized, you won't see it on there). Especially for people with complicated sound setups, the browser plugin might not work right away on install. It may need a bit of tweaking, just like any other audio application.
The other big draw for Puggable is supposedly that you can see and browse other players' information quickly (from achievements to specs to how many emblems they have), but that worked infrequently for me, even on the character that I was signed into. I assume it connects to the Armory, so if the Armory is down or having issues, Puggable will as well. Plus, the whole system is in beta, so it may not be working correctly quite yet. But then again, all of that information is already available elsewhere, so it's not a big loss even when it doesn't come up.
And that's about it, from what we saw -- it's a voice chat app that's built into the browser rather than a separate program. Will people use it? Obviously that browser plugin installation is a potential obstacle to overcome, especially for people who aren't tech savvy and have already heard warnings about installing third-party apps related to World of Warcraft. Plus, most people already have Vent working, and the task of switching to a new voice chat application may be tougher to overcome than the current frustrations of trying to get everyone in a PuG into a Vent server.
After all, the game already has voice chat, remember? (You might not -- no one I know has ever actually used it on the live realms.) If players have stuck with Vent rather than using even an official in-game client, it's going to be tough for Vivox to try and convince people to move over to their service. But you never know -- Puggable is still in a beta form right now, and it may grow more useful or easy-to-use as it gets closer to release.