It's got an electronic viewfinder (yep, the viewfinder is just a tiny LCD, it's not optical - again, that's enough reason to say no for me in an SLR equivalent).
Being an owner of a G1 which also has an EVF, the advantages out weigh the disavantages.
First up you get a massive 100% fov viewfinder, my G1 is around the same size as a 1D viewfinder, you just don't get that on any DSLR around the same price or even the D300s or 7D.
EVF being 1.44 million pixels & at refresh rate around 60hz you get a nice clear flicker free image outdoors & in good light.
EVF also has all the info in front of your eye including histogram
The only downsides to current EVF's is that in poor light like indoor lighting, the EVF becomes grainy as they automatically up the gain, but the upside to this is you can see what your shooting in near darkness, something you would find difficult a optical viewfinder.
EVF technology is getting better with every release, the current SONY A33 & 55 EVF is better than my G1's also can be said about the G2 & GH2 were they managed to lessen the blackout when continous shooting.
I've been using an EVF now for 2 years & actually wouldn't go back to using a optical viewfinder.
The EVF viewfinders are the future for big sensor camera's, Sony were the first to bring this to the DSLR market, others will follow at some point ie Canon, Nikon & Pentax it's only a matter of time till you say goodbye to optical viewfinders and mirrors.
And eventually when the tech there you wonder how you managed with just an optical viewfinder.