Our garden is north/north west facing. It is approx 70ft.
The sun in the summer is high enough in the sky that, at some point, every part of the garden is in the sun in either the morning or afternoon, and there's a good portion of the day where the garden is all in full sun.
There is probably 3-4 weeks of the year where all of the garden is in shade, and then the sun starts to creep back from the end of the garden coming down towards the house.
We only really use it in the summer so don't find it so much of an issue, but we're lucky that it's quite long.
However, it makes you use your garden in a slightly different way. We have our main sitting area at the end of the garden as that is in the sun the most throughout the year.
It's also worth considering (if you have a patio by the house) what type. The previous owners had brick paving just outside the house and, due to all the joins and the fact that it is the part of the garden in the shade the most, it gets full of moss every year! We are planning on changing this to decking.
So it doesn't have to be a deal breaker by any means but it depends on how big the garden is (as the house will cast a shadow on it some of the year) and it makes you reassess how you use it