Has anyone used these pots as sold by twowests?

http://www.twowests.co.uk/TwoWestsSite/product/PP.htm

Im interested because they seem cheap as chips and yet they are
new/uniform looking (as i want to grow plants in them i can then sell
for charidee so presentation is important) as well as probably being
quite efficient with space.
I am concerned they will be difficult to use tho, say having a similar
issue that black bin bags have when you are trying to fill them -
constantly falling shut.
Any experiance??
thanks
sarah a