Complex sentence: While critically acclaimed, the One series has not received much consumer attention and sales have been disappointing, due to HTC being outspent on marketing by Samsung and Apple, as HTC instead had relied heavily on carriers to promote its products.
Split into simpler sentences: While critically acclaimed, the One series has not received much consumer attention and sales have been disappointing. For one, HTC has been outspent on marketing by Samsung and Apple, as HTC instead had relied heavily on carriers to promote its products.