What Are The Benefits Over The Other Materials Out There?

Ceramic Heavy and fragile, requires a kiln (highly specialized to use, expensive, and needs a dedicated space) There is a definite size limitation too. Beloved pieces randomly explode.
Paper Maché Regrettably, it will disintegrate in the presence of the morning dew. Rain is out of the question, and snow is impossible
Sculpey, Fimo, Premo, Etc. Indoor only ($$$), small figures only, less than a foot tall. Cower in fear of being left outdoors.
Epoxy Based Clays Pal Tiya Premium is a cement based material and is not an epoxy. Epoxy is a form of plastic, a two part system where a catalyst and resin are mixed together to harden. Premium uses water instead as it's mixing agent. 
Some epoxies are mixed with talc-like fillers to bulk them out to a putty consistency. These knead-able epoxys (Apoxie, Magic Sculpt) are typically used in small and midsized pieces, being generaly accepted as too expensive for larger work. Anything larger than a two foot figure would be preferably sculpted in clay,  molded in rubber, and then cast in another material. 
Epoxy has a direct linear cure, once mixed, it begins to harden steadily and quickly to a hard finish. PTP has a slow cure and a softer, longer working time in a pliable state.  
Epoxies are a strong material, and a good workable putty, but don't have the consistency and nature of a traditional sculpting clay. Pal Tiya Premium shares the same touch and feel as a classic ceramic based clay. 
Plaster, Hydrostone, Gypsum Dissolves within a year in the weather becoming a poetic metaphor for the "Relentless Advance of Time on mortal objects".
Wood Time consuming, difficult to do subtle human figures well, repairs and alterations are difficult. (A bonus; the unsuccessful sculptures can still be used to heat the house)
Stone Time consuming, difficult. A modest sculpture can weigh as much as an engine block, mistakes are difficult to repair.
Concrete Can be very strong and can go very large. Fragile by itself, it requires steel/chicken-wire armatures. Very thin delicate-as-a-teacup details are unlikely to survive. Might need welding; see "Steel".
Bronze Are you kidding?! Out of the question! We kept tripping over the cat as we moved the 1300 C boiling metal crucible off the stove top.
Steel Needs welding equipment ($$$) and welding in my apartment is discouraged. Rusts.
Plastics Requires molds ($$$), often highly toxic, specialized equipment, The safety sheets can be scarier than Stephen King novels.
Fiberglass Toxic! ($$$) The heavy chemical smell will seriously upset your mom/ neighbors/local militia.
Darjit Pal Tiya Premium was designed to be a easy "add water and mix" product. All the work of making it weather proof, super strong, thaw resistant, and silky smooth has been done in the lab. Every component was chosen carefully to create a specific optimal mix. Darjit is made by each sculptor personally and each mix is different.
Plasticine We LOVE Plasticine. It's fun watching creations melt outside in the hot sun. "I'm Meltiinng! What a world, what a worrlld!".
Mashed Potatoes

We've found it's totally brilliant for making replicas of Devil's Tower Wyoming.