DPreview tested the lens and it performed very well (if you consider the very wide zoom range). Like other Olympus MicroFourThirds lenses it suffers from average Chromatic Aberration which in any case is easy to correct in post-production. I bet Olympus is working to add CA correction via firmware update.
Read the review: http://dpreview.com/lensreviews/olympus_m_14-150_4-5p6_o20/
Reminder: Also SLRgear reviewed the lens 10 days ago!