depends i would say, let me give some enlightment.
do u prefer to shoot at night or daytime if it's portraiture? the answer is obvious:
if u prefer at night, the wide open F1.8 is what u need. stage show, event, low light, distance, natural light will benefit from the F1.8
but if u choose seldom to shoot at night, or u would use WLflash for night portraiture, and daylight... 55200 has better Bokeh at 200mm then F1.8 and nicer easier to control DOF. especially when u shoot at daylight, 55200 give decent speed shutter speed (then F1.8, where a lot of time will reach the limit 1/4000 and overexpose)
if money allows, grab boths.................... and a F58, and 1750F2.8, and CZ1680, and SP90, and 1118, and 70200G, and A550. then thats about it.
Added on November 6, 2009, 9:22 ami find the video very erm,... funny, i dont like the way the guy talk, like we are in kindergarden...LOL, and 40% of the video are like trying to sell u things. LOL... anyway, it answer a lot of question people always ask, raw or jpeg, bounce or direct, F2.8 vs F5.6, AWB vs WB etc etc etc

fast fast go watch...
*edit typo... later i attack the flash again...

I do shoot at night too but less. Anyhow, is the 55200 suitable for landscape and architecture? Or the F1.8 50mm would be a better choice for landscape and architecture?
Tainted: The Sony 55-200mm F4-5.6 DT is the same just with a 55mm filter thread, same as your kit lens.
And yes, it would be optically better than the Tamron 70-300mm F4-5.6.
When you are saying that its the same, so are you saying that its pointless to go for it as well? Since its the same as my kit lens?