Maybe it is the case of you liking Stealth games more than FPS. Halo was a launch title in March, whilst Splinter Cell wasn't released for at least a good 6 months later - November I believe. (Splinter Cell had more development time, Bungie was under pressure for a launch release)
I finished both the games mentioned, and even though I enjoyed Splinter Cell I liked Halo more. Everyone is different, and has there own personal tastes.







