I could write for an hour on this one. The Android version is more robust and has more features but the iOS version has a cleaner, more reimagined look. The iOS version - which is only 2.5 months old - has driving, walking, and public transit directions but is missing bicycle nav. Overall, they both get the job done, both have street view, satellite, etc. IMHO, the iOS version is overall, just as capable and functional as the Android version, but it lacks some extra features - which will likely come in future updates.
Also, IMO - the deciding factor between an N4 and the i5 will come down to other features of the respective phones since Google Maps is fairly equal (give or take a few features) between the 2 platforms.