I'm a little worried, it being Skyrim and all - and the land in-between being quite varied (from tundras to forests, grasslands to mountains) that there isn't going to be as much variation in the cities themselves. Especially not on the level Oblivion had.

The demonstrations showed around 3 towns (one where you actually see jobs) and 2 others in the distance that looked very similar.

Will there be towns like Bravil/Imperial City or will they all be like Bruma/scarcely populated as shown in the videos (in terms of appearance)?

I don't think there's enough information to tell yet, but I think one of Bethesda's main goals was to improve on things Oblivion lacked. So some diversity in the towns is very likely.

Here's some screens of the towns we have been shown so far:

Whiterun: http://www.elderscrolls.com/skyrim/media/screenshots/whiterun-0/
Riverwood: http://www.elderscrolls.com/skyrim/media/screenshots/riverwood/
Markarth: http://www.elderscrolls.com/skyrim/media/screenshots/markarth/

There could be more, these are the ones I know of. :spotted owl: They look pretty varied to me... :whistling:

I read in some magazine forgive me for not recalling the exact name but anyways i read that each city will have unique architecture and enviroments

If Riverwood, being a "small" town, is lively as we have seen...