If you're a Halo fan, it is absolutely worth it, though, admittedly, barely. Halo 1, 2, 3 and 4 with all campaigns and, nearly priceless to any Halo fan, Halo 1 and 2 online matchmaking, both as they appear and play as the originals. And that doesn't even include Halo 5 AND 6 (if this bullshit "10 year console" pans out like Microsoft hopes).
Anyway, if you run your Xbox at 720 on a 720 screen, it'll run at 720 with no sort of input lag.