It's not the first time I've linked to an Alvin Wong article - he may be young but he's a great reviewer and with a mountain of Symbian expertise already. In this nicely illustrated piece he summarises his two weeks with the Nokia E6, concluding "It’s easily my second favourite Symbian^3 device after the N8, and one that I can recommend without reservation to anyone looking for a device of this form factor." Backing this up, he lists the reasons why the E6 is superior to the E7, interestingly. More quotes, links and a photo below.

From Alvin's final report:

What Nokia has created here is a sleek, solid, well-designed QWERTY monoblock smartphone that manages to keep up with the times, can do everything that larger and more expensive smartphones are capable of doing, and does what it was made to do really well. Sure, it’s still saddled with dear old Symbian, but the E6 is competitively priced (especially in comparison with the overpriced BlackBerry 9900) and the Symbian UI is still a great fit for devices of this form factor, surpassing Android in terms of how well it adapts to landscape displays (at least every single app displays in landscape orientation) and beating BlackBerry OS in raw functionality and customizability. 

He concludes:

If I weren’t already considering a move to Android, I’d definitely give the Nokia E6 a serious look as an upgrade from my E5. Honestly, I’d take the E6 over an E7; the microSD card slot, user-accessible 1500mah battery, easy-to-use volume buttons and its lighter and smaller build are huge points in the E6’s favour. It’s easily my second favourite Symbian^3 device after the N8, and one that I can recommend without reservation to anyone looking for a device of this form factor. It is, quite simply, the best monoblock QWERTY device you can buy today.

Here's the right tag to see all of Alvin's writings on the E6.