For example, when they draw a circle, you can see the pixel, or in my image, the pixel look invisible !
In tkinter, you draw a circle on a Canvas widget.
To make the widget visible, you need to use a geometry command such as place, pack, or grid.
Tkinter was designed to look like motif, which was popular for a long time.
Qt4 has a more modern look and feel, and has a plethora of predefined widgets and examples.
If you look at their site, and examine some of their screenshots, or even in google image, query 'Qt4'
to get some very good examples.
Tkinter can also look very sexy, see the image at the end of this post: http://www.python-forum.org/viewtopic.php?f=12&t=20968
every time that I see a GUI, like Tkinter, or PyQt, the design doesn't look good
Don't forget that everything beautiful in life is made up of some very elementry items that don't always look good by themselves,
yet the end result may be stunning!