It IS bad. Unfortunately I am not aware if the game simulates correctly deflation (negative inflation) which is even worse. Perhaps a future patch could add a big contentment penalty if that situation arises.

Most importantly, inflation should be
under control. If it remains stable (even relatively high, but not more than 10%) you are doing well. Yes things will cost more to construct or buy (import), but that's about it. Economic sunrise events and political actions can decrease it now and then. My advice is simply: do not obsess over it. It is harmless, unless entangled in a cutthroat war. But in that case, your problems are much worse than simple inflation.