I just bought a new LT-46148, which is substantially similar to the 149 Series, PQ-wise at least, and have so far been disappointed with the quality of upconverted 480p component video from my DVD player and Wii. On other TVs, including a Mitsubishi 144 Series I had previously (panel failed twice and Mitsubishi authorized TV replacement), I have turned sharpening down to minimum or a low value and got a decently sharp image with no visible halos or ringing artifacts.
With this new 148 Series, 1080i and 1080p HDMI signals look great at minimum sharpening. My 480p sources, a progressive DVD player and a Wii with component breakout cable, look terrible at the lowest sharpening level. I see dark halos around high contrast edges, which looks almost like a double-image. This seems very strange. If I crank sharpness up to 15-25, the dark halos are minimized, but are replaced by somewhat less visible light halos, typical of over-sharpened video.
Anyway, the upconverted 480p component video on this TV is just not the same quality as with my older LT46144. It has more artifacts and it just looks blurrier overall. Does anyone else see these issues with their 148/149 TV with 480i/p sources? Has there been a software update for this set? Mine has a build date of May 2008.
I did find a review of the LT52149 which mentions this issue, so I'm not optimistic that there is a solution: UltimateAVMag.com review of LT-52149