I was in Isaac's playtest (empathy unique thing). I thought I'd toss in my own quick synopsis of my impressions.
--I know nothing about the designers, and frankly don't care. In the end, it's the quality of the product that matters, not who made it.
--13th Age has *incredible* potential. There were a lot of aspects to the game that appealed to me immensely, and if it delivers on that promise, my next campaign will likely use the system.
--I particularly liked icons, backgrounds, one unique thing, and the overall tone of the writing. Isaac described the writing as 'transparent', and that's the perfect word for it. The classes did seem to be well individualized too.
--I'm somewhat neutral on the escalation die; I suspect it's a gimmick that shouldn't be needed most of the time with a good GM--but a reasonably good way of ending a battle if (as I have occasionally) the GM makes a mistake on a combat's fun or overall length.
--I'm neutral on how weapons and armour are basically flavour. Weapons are dice tiers and armour is 'if you're wearing the appropriate category, your AC is (this)". I've never been happy with Christmas Tree DND, so overall I like the idea, but I see this as one of the more controversial decisions.
--Not enough options in the current playtest. I played a bard too for example, and could pick three class features...out of a total of eight, two pairs of which were designated mutually exclusive. There were only two to four new bard spells to choose from each level. That sort of theme seemed prevalent throughout the book, not just the bard class. It was a playtest though, so hopefully the final version will have more options available.
--Based on what I saw from the playtest document, I'm frankly skeptical they'll be able to deliver on the many, many promising features of the system. Great potential, but August/September doesn't seem to be enough time to develop them. However, this is also my first playtest of a RPG still under design, so I may be being overly pessimistic. --And I am basing this comment on my "too few options" point above; the fundamental concepts themselves are reasonably well finalized atm.
Bottom line, based on what I saw I will probably not preorder it. I was very impressed with the game's potential however, and I will take a look at reviews of the final product and buy it if they do manage to deliver after all. It may be that buying it to lift certain mechanics and concepts out to your favourite system might be the way to go.