330d has a lower 0-60 time plus more torque, 328i is perhaps more 'nimble'. Interesting article on how pure figures are misleading though.
For me the close competitors are 335i (3.0L, 0-60 in 5.5s) vs. 330d (3.0L, 0-60 in 5.6s) and 320i (2.0L, 0-60 in 7.6s) vs 320d (2.0L, 0-60 in 7.6s). If there was a 'hot' version of the 320d, say a 323d that might be a more natural comparison with the 328i? Anyway, I say we enjoy our respective cars and hit on the Merc's and Audi's instead