I had only seen reviews of the Endless Recorder Notebook with Regalia paper so, in a way, I made the purchase based on those reviews and faith that I would like it. I purchased 3 notebooks and a creative block and am extremely happy with my purchase!
The notebook itself is excellent, this review is more about the new Regalia paper. I didn't think anything would top Tomoe River, but for me the Regalia has done it! There is a little more shading and sheen than TR and writing appears a little broader - this might not suit everyone but perfect for me. Paper is a little thicker so there is virtually no show through - nno problem whatsoever writing on both sides, even with the broadest of nibs. Sheen etc. is similar to what you can expect from Cosmo Air Light, but there is less of a problem with places where your fingers have been resting becoming unusable (less but there is still a little bit of this, the one area it falls behind TR).
Overall, it's my new favourite paper!