I got both at GenCon and the Adepts is definitely the higher value. The ritual magic rules are straightforward and seem playable, and no matter what sort of game you're running, there's probably a few powers in there you'll want to include. And the supernatural items rules will probably find use in most campaigns.
The Experts is not so valuable. There's a HUGE array of feats that are all nested in just the way True20 isn't, and most of them are really things that I would rather just rule on the spot. There's tons of feats that let you run social groups, which I can't imagine ever using, and a bazillion feats that offer variant ways to screw people up with your Sneak Attack, or your Feint, or whatever. I dunno, it seems against the spirit of True20 to me. I like the freewheeling nature where if a player wants to confuse an enemy so much he gets a penalty on his Dex, he just needs to roll high and give me a good rationale, rather than taking Entangling Feint (which requires Diversionary Feint, which requires Beguiling Feint, which requires Dazzling Feint, which requires Improved Feint). Likewise, the proliferation of challenges and uses for skills doesn't really add much for me. I don't need rules to use Survival for making, finding and reading trail signs -- I can make that up on the fly.
And the equipment list includes "Juggling Equipment".
I don't think I could have done a better job -- I just don't think there's really a book in the Expert, frankly. And maybe some folks are looking for this sort of thing and it's just me, but this book really didn't bring me much value.
My advice is to get the Adepts book but not bother with the Experts.