as a bitchin' pom myself
'Even though I've been to Shanghai only once for few weeks'
this kinda invalidates what you have to say - since you have only a superficial knowledge of Shanghai, of course you'll think it's superficial. you must see this right?
I've lived in both BJ and the shang, both for more than 2 years (I realize this doesn't give me exclusive rights to "The Truth"), in my experience both have the good and the bad.
I like both cities(and sometimes hate em both too) Overall I marginally prefer living in the Shang because the local people are less likely (proportionally) to hate me for no reason (had a few pretty lame Lao Beijing interactions)
I hear many (dumb) people living in BJ hating on the Shang, and (dumb) SH people cussing out the Beej.
As you can probably tell, I think it's pretty lame...