All terrain pushchairs can either be three/four wheel "Air Tyre buggys" or with solid tyres. The benefits of an "Air Tyre buggy" is a better ride for baby and easier to push for you the downside is that they can puncture. There are also pushchairs with solid tyres which do not puncture.
All terrain pushchairs are great when the going gets a little tough. The larger wheels cope easily with grass, shingle, sand and even snow. All terrain pushchairs tend to be larger than conventional pushchairs so it makes sense to check to see if they will fit into your car.
If you are a go anywhere type of person then a All Terrain pushchair may the right choice for you however it is worth thinking about a more conventional pushchair and use a front carrier in the early days or a rear carrier for 6 months plus.