I like this latest post at my Pentax Discussion Group, in which the poster speaks out exactly what I have been thinking in the beginning of his post:-
http://tech.groups.yahoo.com/group/ricehigh_pentax/message/630
"So far, regardless of what anybody says, I have been able to personally confirm many of the results that dpreview got in their tests. Just wanted to say this in case anybody has problems with their results!
So here is another blow to our beloved K-Bayonet mount. It seems we are dying for good these days, with prices going up for less quality all the time.
http://www.dpreview.com/lensreviews/pentax_55_1p4_p15/page5.asp
Quotes from the conclusion page:
Unfortunately though, we have serious concerns over two issues with this lens which have to temper our enthusiasm; namely optical alignment and autofocus (which are quite likely related). Over the course of what has become a rather protracted regime of testing, we've looked at three samples of this lens; each has shown a clear tilt to the focus plane, most pronounced in the first sample, and least problematic in the last (which we finally decided to use for the published tests). This does more than simply mess up our studio tests - it clearly results in real-world image quality and focusing problems too. In fact we've never before seen a lens so capricious when it comes to focusing - we're used to F1.4 primes being challenging for cameras' AF systems, but the 55mm was most difficult of all. We couldn't get any of the tested samples to focus sufficiently accurately for reliable shooting wide open without resorting to focus adjustment, and the amount required on our K20D body (which focused the FA 50mm F1.4 just fine) was huge, a full +10. The lens worked better on the K-7 we received during the course of this review, but still needed adjustment for best results, although curiously in the opposite direction (-3); but on the K2000 we were left high and dry, unable to achieve accurate focus at all. Based on this experience, it becomes difficult for us to recommend the lens to owners of cameras other than the K20D and K-7, on which AF adjustment isn't available, unless you can test it to your satisfaction first.
The other big problem we simply can't overlook is the distinctly high price. At the time of writing we're looking at $650, which does seem rather steep when compared to the alternatives; $500 for the excellent Sigma 50mm F1.4 EX DG HSM, or a mere $250 for the outgoing Pentax smc FA 50mm F1.4 (by way of comparison, Nikon's new AF-S Nikkor 50mm F1.4G retails for about $470, and Canon's EF 85mm F1.8 USM full frame portrait lens, $380). Now it's fair to say the 55mm F1.4 is much improved over the old FA 50mm F1.4, but the Sigma is a different proposition entirely. It sports both excellent optics and ultrasonic-type focusing, placing it very much in the same league as the 55mm. However it's not weatherproofed, and noticeably short for a 50mm lens (we'd place it closer to 47mm, giving a 70mm equivalent on APS-C), making the 55mm a nicer length for portraits.
So providing a final recommendation to this review becomes very difficult. When this lens works properly, it's one of the best portrait lenses that Pentax users can currently buy. But getting it to work properly has been the source of much frustration, and we consider that, especially given the price, it really should work better out of the box. If you can afford the asking price and get the lens functioning properly, you will certainly be delighted; but for most users we can't help but feel that the Sigma, or even the older 50mm F1.4, will be a better (and safer) option."
In fact, I think this time the DPR reviewers have nailed the problems quite dead accurately and they have described the current difficult situation faced by we current Pentax users very well.
Btw, sometimes I just wonder even if the QC of those latest current Pentax products are poor, Pentax/Hoya have been very unwise whenever they sent a test sample of any gear to DPR, it seems that they had never checked the samples themselves, technically, i.e., to finally check if there were any problems with the gear that were to be tested. It also seems that those Pentax officials at the Japan HQs just let Pentax UK to deal with DPR alone but in fact those DPR tests affect the sales of Pentax products worldwide much (as their readership base in reading their reviews is still very huge). All in all, it's not only about the poor and inferior quality control at the Pentax lens factory at Vietnam, it's also about their poor PR and publicity works and they have just been too causal when sending samples for testing - How come they could not be a bit more alerted and took more awareness when they sent DPR their Pentax test samples?
Nevertheless, to make some balance of DPR's experience, findings and results. I do believe that the DA*55/1.4 should still be a good lens optically (putting aside the really problematic QC issue and the ridiculous current high price tag of it), see the tests and results below. Still, the lens at least looks fine to me (and optically it is good to excellent, on APS-C DSLR bodies):-
http://www.informatik.uni-bremen.de/foto-ag/DA55/DA55.html (on K-7 and K20D)
via http://ricehigh.blogspot.com/2009/02/da-5514-vs-fa-5014-measurebating.html
http://www.slrgear.com/reviews/showproduct.php/product/1235/cat/45 (on K10D)
And, as for the slow focusing of the SDM, this is of no doubt and actually nothing arguable - ALL the testers/reviewers are saying the same so far!