Spigen from my experience has been great to work with, always fast on shipping and customer service is quick to get back to me. Its ironic that I had ordered the LG Optimus G Pro last Saturday figuring the S4 32GB wouldn't come for weeks or months so I shipped back my screen protectors AND then bam, ATT announces its arrival for the 10th. Well I chose to get the S4 32GB but I had already shipped back my Spigen screen protectors, canceled my case, really chaps my bum on this.
Still all in all I decided to order the Glas-tR after all (after seeing how well it fits on the S4) and now they have even more awesome cases. They even created a window sleeve case with sleep mode, a case for those like me who opted for the flip cover S-View case and many others. Glad I don't have to cob job a TPU case to work with it.