Sooo, i had the opportunity to put my hand on this lens today, and to compare it quickly with my like new SMC DA*55/1.4
Here are my first-hand findings :
1- really heavy, solid built and also very handy , whilst the older DA* might get a litle bit more of a softer build materials (and has no super aero-bright nor HD coatings)
2- pretty qwicker AF speed, though not that faster in AF lock, due to the higher moment of force (K-1 in fw 1.5) and despite slightly shorter distance span (less graduations an AF rotation angle)
3- top of the notch resolution even @ the widest aperture. The DA* poorly compares here (f/1.4), and this is worst near it's minimum focus distance (respectively 40 and 45cm) and getting off center
4- "same" AF lock and potential irregular F/B focus issues
5- very comparable bokeh and colour rendering in interior daylight
6- better vignetting result with the DFA*, though this aspect is not really a problem with DA* if you dont need the highest quality file-corners.
So basically, and not pre-empting forth-comming deeper comparisons, if you are not reluctant with "overload", and need the full K-1 resolution with the "best-in class" rendering, get this new lens.
If you cope for general use and/or compressed images, also not using that frequently ultra-wide apertures for ultra-crisp images, the DA* still keeps some arguments, even in FF mode (landscaping, mid-aperture portraits, …).