The lens IS nice - it gives beautiful images, and is sharp wide open.
That said, I sold mine to finance the purchase of the E-PL1 and 20mm f1.7.
The problem with the lens is that on SLR systems, it really doesn't focus well in low light using phase detect.
It is extremely accurate to focus in CDAF mode - which bodes well for micro four thirds bodies (af does work -
Compatibilities of DMC-GF1, DMC-GH1 and DMC-G1 | Compatibility | Digital Camera | Product Support | Support | Panasonic Global) - and in low light, sometimes cdaf was the only way to focus.
It's not a fast focus when using cdaf in low light - so while it CAN take a great picture in low light due to the sharp f1.4, but would be slower than you'd like - or require manual focus.
e.g. 25mm f1.4
http://beomagi.ath.cx/gallery/2010%2...y/P2208802.JPG
All in all, I do prefer the 20mm pancake. I think it is sharper than the 25mm paleica in the center, and can live with 33% less speed. AF is far faster, and of course, there's the size...
e.g. 20mm f1.7
http://beomagi.ath.cx/pics/2010%2005/15/P5150303.JPG
For the price and size, i'm really thinking I could have a VC Nokton 50mm f1.1 and be happier.