Really? I haven't heard anything good about MME.
I think Mordenkainen's Magnificent Emporium is very good (so there you go - you've now heard something good!). The Tome Show episode where they reviewed it also gave it uniformly positive reviews. I haven't actually heard anything negative about Mordenkainen's Magnificent Emporium - well, I guess until now!
As for WotC "hitting their stride" it's hard for me to say because I've only been playing the game for a little less than two years. But I've certainly enjoyed the stuff that's come out recently.
To be fair, I also really enjoyed stuff that was coming out last year at this time - the Rules Compendium, Heroes of the Fallen Lands, Heroes of the Forgotten Kingdoms, Monster Vault. The Red Box isn't very good in my opinion, and the DM Kit itself isn't exciting if you already have DMG 1 & 2, but the Reavers of Harkenwold adventure in the DM Kit was a lot of fun at my table.
I wasn't excited about Dark Sun last year, and I didn't much care for Heroes of Shadow or The Shadowfell: Gloomwrought and Beyond. I liked Monster Manual 3 last year (though I thought Monster Vault was in a league of its own). I wasn't crazy about Player's Handbook 3.
So, based solely on my own opinions, WotC has been hitting its stride with printed materials since the Essentials line came out in late 2010, with only a few misses (Red Box, Gloomwrought, Heroes of Shadow) and far more hits (the rest of Essentials, Heroes of the Feywild, Monster Vault - Nentir Vale, Gardmore Abbey). This is just my own opinion, though, and I know that other folks may, for instance, love Heroes of Shadow and hate the Essentials books or something like that.