Kowloon actually consists of several areas that have distinct characters.
For example, the area around Tsim Sha Tsui is more upmarket, with many expensive hotels.The famous Peninsular is there, one day I saw 6 helicopters land on the rooftop helipad. It is where the arts centre is located with the avenue of stars on the waterfront.
Mong Kok is one of main areas for buying photo equipment, but I managed to avoid visiting and spending money there. Mong Kok was showing signs of urban decay, even years ago when I stayed in apartment of a friend of mine in a shoe box sized room, which is pretty typical of the older areas in Hong Kong..
While the area around Sham Shui Po shows a lot more evidence of urban decay, and is mostly down market.
In Sham Shui Po, I found the best ever custard tarts, locally known as Chinese cakes, at a small bakery a few blocks down Kweilin street on the south east side of the MTR station. Buy at least 6 when you visit! And see if you can stop at that number! I think it was the Dynastry bakery but you'll know when you find those tarts!
From Sham Shui Po MTR exit to the south east, it has a lot of street stalls selling electronic bits and pieces. If you need a European power charger for your mobile phone, one stall had hundreds in a box. I guess everyone who buys a mobile gets that one which they can't use with the clunky British power sockets used in Hong Kong. Plenty of shops selling various electronics, including surveillance systems, video and audio misers, cables, even real 'old' HiFi equipment from valve amplifiers to record players to CD players, quite unlike most modern sound systems, which are rarely HiFi. And the ubiquitous mobile phone shops. Everyone in Hong Kong seems to have a mobile phone, and it is rare to see people talking to each other face to face.
The only more upmarket place is the Dragon centre, see photo of atrium.