Its a bit of a learning curve. Going from E-500 to 510 took no time to get adjusted, but the E3 takes a lot of getting used to. The viewfinder is indeed awesome. I did a little back to back and the difference is AMAZING.
and indeed, the focus is quicker [though not incredibly] with my 12-60. Also more accurate, there were a few instances where the 12-60 had difficulty focusing when mounted on the 510, and I recreated them with my E3. It still struggled a tad at first but in the end locked on 100% of the time [better than the 50% with the 510] and much quicker too.
There are some things that bug me, the arrows no longer have WB, ISO, Metering, and AF [I think] assigned to them like they did on the 510. This means a lot of "extra" buttons thrown around the body almost randomly. I feel that there was NO logic used with these buttons, but I've already grown used to most of them, still I often have to bring my camera down to make adjustments.
Im a little disappointed also that having two scroll wheels isnt as awesome as I imagined, but I dont really know why I imagined it would be so great. I guess only having one made me envious.
The HLD-4 Grip? Eh I dont know if Ill keep it, I may sell it. It doesnt seem that its THAT much more comfortable shooting with the grip compared to tilting my hand. And its very thick and cumbersome, heavy too. And I'd prefer it had a shutter release on either end like the OWNusers had on the 510 models.
But enough of the gripes... The performance is stellar. I do not fear going into ISO800 anymore, or even 1600 if I have to for that matter. I also like that it can bracket. I can do HDR photos without a tripod using bracketing and the 5fps shutter rate.
I have yet to try out the weather sealing, I got the camera used and the cable sync port cover is missing, [little screw] so I dont want to risk it. Ill order another and get back to you guys