Is free garden design software any good?

[PorridgeAgainAbney]

I am trying to work out planting ideas for my front garden. It's not a simple garden - there's no grass, it's just a series of different shaped beds criss-crossed with paths, approx 10m x 8m. The garden is also on an incline (side to side, rather than front to back) so I'm finding it really hard to to visualise how the garden will look from different viewpoints!

I can't afford to buy any programs (unless anyone knows of something really cheap ) so wondered if anyone has used any free 3-d software and thought it was any good?