Amazon's finally getting around to a much needed update for its Instant Video app on iOS today. Version 3.0 adds the ability to stream movies and TV shows in HD. Yes, everything's been standard def until now. The update also allows you to watch content using your cellular data; previously, Instant Video simply wouldn't work unless you were on Wi-Fi. Obviously people should be mindful of their monthly data limits while doing this, and thankfully Amazon has also introduced some quality settings that determine how good video will look — but also how much data you'll suck down while watching Transparent or Mozart in the Jungle.
The "Best" setting should probably be reserved for those of you with unlimited data plans; Amazon says streaming at that quality level for an hour will use up 5.8 gigabytes of data, which is enough to totally devastate most tiered plans. Moving down to Better (1.8GB per hour) and Good (0.6GB) is a bit more reasonable if you've got hard limits on data usage.
Instant Video for iOS offers similar quality adjustments for movies and shows that you download. But (unfortunately) the app says "Downloaded content will play in SD on this device," so we're not really sure how clear the differences would be here.