Is a grinder upgrade worth it?

I used the same cheap blade grinder for years. Switching to a burr grinder changed more than I thought it would.

Consistency is the whole story. With even particles the water extracts evenly, and the bitter edge I blamed on the beans simply disappeared.

If the budget is tight, a decent hand grinder beats an expensive machine paired with poor grounds. It is slower, but the cup is noticeably cleaner.