Complex sentence: Scott Stein of CNET said that although the iPhone 5S "is not a required upgrade, but it's easily the fastest and most advanced Apple smartphone to date," however criticized the lack of design change over the iPhone 5.
Split into simpler sentences: Scott Stein of CNET said that although the iPhone 5S "is not a required upgrade, but it's easily the fastest and most advanced Apple smartphone to date". He criticized the lack of design change over the iPhone 5.