Scott Sumner argues that there has been both zero inflation and that 100% of NGDP growth was inflation (both since 1964). Tyler Cowen makes a good point about these arguments changing with income. However, Sumner's main conclusion is that inflation is a pointless concept -- in terms of understanding macroeconomic systems.
I think the real answer here is that economists don't really know what inflation is and they fall back on 19th century concepts like utility to ground them. Cowen and Sumner both ask if you'd rather live in 1964 or 2014 with a given nominal income. If that's what defines inflation -- hedonic adjustments and utility -- then I'd totally agree with Sumner: that's pointless.
But it is in this arena that the information transfer model may provide its most important insight (regardless of whether you picture money as transferring information from demand to supply or from the future to the present). The idea is spread over two posts, with the second being the main result:
When money (M) is added to an economy, that means more information is being moved around. The difference between how much more information could theoretically be moved around with that money (proportional to M^k) and how much more information is empirically observed to be moved around (proportional to measured NGDP) is inflation.
Inflation has nothing to do with the specific goods and services being sold at a given time. It doesn't matter whether it's an iPhone or a fancy dinner. It doesn't matter whether it's toilet paper or bacon. Inflation is an information theoretical concept, not a philosophical utilitarian one.