Is this true? I jumped on UC and Gears 1 about a year after both were released and I couldn't stand Gears (though admittedly I only played about 5-6 hours). Ironically I'm replaying Uncharted 1 right now to clean up trophies in the first time in almost 2 years. Obviously both series are well loved, but was UC1 really that looked down upon? It holds up ridiculously well even after having played the sequels, in my opinion of course.
UC1 is just as good as UC2 and UC3. UC1 had some of the best gun porn in my opinion. I still have many fond memories of the game (I played it around launch I do believe). Gears 1 was immensely fun in my opinion, but had one of the worst narratives I've ever played. So, yeah, Gears kind of loses its appeal over time, but that's what the MP's for. And in this case, it's probably what helped the game sell.
Regardless, Sony's American studios have a tough time charting, being that Sony is commonly recognized as a Japanese company. Microsoft is American, and Gears was one of the strongest titles released in 2006. Gears was Halo with bros.