I had a 42" Panasonic 720p Plasma. Which I baught from Costco in 2008 for $840.00, before getting this TV. Although not loaded to the rim with features it should more than cover the needs for most, if not all buyers......especialy for $650.00!
PROS: Plasma tech, Big beautiful 50" screen(1366x768p....not 1024x768p...FYI once u get past 42" ALL 720p tv's are 1360,1365, or 1366 by 768), comes with base already attached, no signs of burn-in(even in the first few weeks, but take the 100-200 hour break-in time seriously!), ECO key, 3 1.3b HDMI's(accepts signals up to 1080p...FYI the tv will then down convert signal to 720p), 2 component(accepts signals up to 1080p FYI.. again tv will down covert signal to 720p)/(one of which can be set as a 2nd composite imput), PC imput, 1 composite/S-video imput(FYI S-video will overide composite), semi-backlit remote(does not come with batteries), almost perfect black level/shadow detail, little to no noise, great volume(mute holds your volume level), good speakers(although not quite as good as my Panasonic), uses less power and produces less heat than my 42" did!, very good color(once you fiddle with the settings), accepts a 24p signal(via HDMI and 3:2 pulldown),very little color banding, sleep timer goes to 3 hours, very bright(sometimes too bright!),exellent motion(which is normal for plasma!), and makes non HD,HD cable,Blu-ray,DVD,HD DVD, XBOX 360,and my PS3 all look better than ever!
CONS: Screen is too glossy(my Panasonic had a anti-glare filter), imputs take a tad too long to change/come on, no numbers in the picture settings menu(which makes it hard to set and/or carry over your settings to other imputs), both red and contrast are a pain to get 100% right on, stereo and coax digital audio out NO optical, skimpy user manual/menu system(figure it out yourself style/typical Sanyo!), no explination for what each aspect ratio setting is for, NO color temp controls(although this tv seems fine without), audyssey volume fuction confusing, and room light sensor doesn't judge light correctly.
Other than the few negative things I listed, most of which are not really big deal breakers... this TV is GREAT! A key thing to remember is your tv's only as good as your sorce and you cables.
As far as quality, I've never personaly had issues with Sanyo products. In fact Panasonic as of Dec 2009 has owned Sanyo. Even before then Sanyo has had close ties with Panasonic,Sony, and Samsung for many years. Which includes using Panasonic,Sony, and Samsung parts in their products(this tv in piticular uses a Panasonic plasma panel). Of corse someone has to get a lemon(s), but that goes for any product you buy. Nothings 100% for sure, just sheer odds there!