I jumped from the D7000 to Sony's NEX-7 (and 5N) in February and haven't looked back.
While the E-Mount lenses leave a little to be desired, the LA-EA2 adapter (which allows the use of Sony Alpha lenses + gives you PDAF) transforms the camera into a do-it-all monster that makes my D7000 seem ancient.
I've had some people tell me that using an adapter defeats the purpose, but they couldn't be more wrong. The NEX system, right now, offers you the best of both worlds: if you want to travel lightly, you can put an E-Mount lens on and take excellent photos; however if you feel like transforming into a smaller (but just as good) A77 and bring the real glass out, you put an adapter on and you're good to go. In either setup you're taking photos that are right up there with cameras twice the price.
Some days I'd like to imagine that if the D800 was available to purchase when I switched, I'd put heavy consideration into it. But where I'm at right now with photography, in general, it wouldn't have been a smart buy. Unless you shoot for a living, in a studio where every detail counts, or sporting events, I simply don't see the justification in spending $3000 to have photos show up on Flickr (and around the house) looking
marginally better than someone who snapped the same shot, with a P&S, who knows what they're doing.
My two favorite lenses thus far are the Rokinon 8mm F/3.5 Fisheye (E-Mount) and Sony DT 16-50 F/2.8 (Alpha Mount). During the day and shooting action, the SAL1650 on NEX-7 with the LA-EA2 adapter is pure joy. The AF is lightning fast and never has trouble knowing exactly what I want to focus on.
As I've explained (seemingly) across the internet, the NEX allows you to take substantial photos with ease. The LCD (and EVF) shows you
exactly what you're getting -- DoF, Exposure, Focus -- and allows you to compose the shot how you want, snap, and move on.
Being relatively new to to photography, the D7000 was also easy to pick up and get running with, but having take a shot or two to calibrate before really getting in to something kept me from fully embracing shooting the shots I wanted. There was always trepidation about going out of my comfort zone with it, because everything seemed like an endeavor.
With the NEX I was seeing the finished product before I even took the shot, and that let me really explore the limits of the camera and my own ability, really, by enabling me to try and capture absolutely everything that came my way.
One of the killer features that I completely overlooked as a gimmick is the flip-out screen. Coupled with the GorillaPod, you can literally take a photo of anything, high or low, and get the shot you want. Having been to WDW in October with the D7000 and then back again in February with the NEX-7, the park felt like an entirely new playground of photo opportunities.
The TL;DR version of all of this is: yes, it's faster and funner to use than a DSLR because you're getting the result you want right out of the gate.
When I first picked up the 5N, LA-EA2, and SAL1650, I wrote a little review
here with some photos. It's a good read if you're interested. In
episode 9 of ISO5571 I also speak about the camera and my experience with it.
I truly can't see myself going back, the system is that good.
These are some shots I don't think I could've gotten with my D7000, as the combination of a small package and the GorillaPod basically rewrote the rules to what I could capture in the park.