We built this a few years back. I think it is 34x60 and has a 10" seat, making the width seem like 44x60. We used a Tile-Redi pan and tiled it. Check their website. They have lots of different sizes. It feels as solid as the built-up mud pan we have in our downstairs bathroom.
The tub next to it is a deep Japanese style soaking tub (which we virtually never use). Bought that on eBay pretty cheap too. Frameless glass doors are a standard size picked up at Lowes. Those were a lot less expensive than a custom door would have been. Walls are all stone as is the seat and shower shelves. Floor is a Mexican honed limestone that isn't the same as the walls but matches real well. Wife and I had fun tiling this project.