A rigid liner could well be the solution of choice when constructing a pond. Points to consider when making this choice are:
Siting: Is their enough room above and below ground to install the liner? It would be awkward to install one over a services supply.
A Raised pond: Probably the best way of installing a raised pond.
Longevity: Much more durable than most flexible liners.
Leaks: A nightmare with some flexible liners, rigid ones are more damage resistant.
Cost: Installing a large liner needs a large wallet. Several times more expensive than a flexible solution.
In summary, if expense is not an issue then this is probably the most satisfactory solution, certainly for a raised pond. In the past plastic and fiber glass liners were not favored by many authorities because they were not that long lasting (cheaper ones), they were often awkwardly shaped, not deep enough and often garishly colored.
Things have improved considerably of late and all reasonable makes are durable and strong. The shapes are still a bit limiting if you are looking for a really natural effect. These liners also have a serious disadvantage in that you have to choose a shape and depth from a limited range. This means that you are, in fact, designing your water garden under serious limitations.
It could well be that you want your pond to be part of a system of streams etc., this is only possible in practice with a flexible liner. Another drawback is the limitation on size. It is always a good idea to build as large a pond, within reason, as possible. Many water gardeners, ourselves included, end up ‘up sizing’ the original pond at some stage. A reasonably large pond is not really an option with a rigid liner.