Jeff seemed to enjoy it... Maybe... At least he played it a lot. Is it good enough to spring for the $60 so I can play it over the weekend, or is it really just freemium good?

Its freemium good, $60 wont get you anything of worth except time saving. Your best just waiting for the release.

$15 is all I would pay - to get a better choice of heros - but as ppl have already said, there is no way of trying them out before buying so it is a bit of a crap shoot.

It is absolutely not worth buying a $60 pack to get in early for one weekend. This thing "ships" on Tuesday so you'd be better off waiting until next weekend and playing it for free.

That said, the "founders program" is supposed to end before launch so if you really, really, really want a specific premium pack then it might be worthwhile to buy it now. I am sure that they'll have new premium packs available on launch but I don't think there's been any information about those yet.

Edit: Also worth noting; Early access seems to have been eaten up by a lot of server downtime so, seriously, don't buy in for early access.