Infinity Blade has been more successful than Shadow Complex. "Hugely successful," in fact.
Right now, if you check the leaderboard data (best overall score) for Shadow Complex, you will see the names of 545,023 players. While Rein's comment doesn't necessarily confirm that Infinity Blade has been downloaded more times than Shadow Complex, the former game's lower asking price – $5.99 versus Shadow Complex's $15 – would make it "more successful" either in terms of downloads or revenue.
If it's revenue, our napkin math indicates the iOS-exclusive title being downloaded by at least 1,362,557.5 people, two-and-a-half times the total number of entries on Shadow Complex's leaderboard. If we're talking number of downloads, Infinity Blade should have at least bested Shadow Complex's 545K units.