Good prose can salvage a bland beginning, and an interesting beginning can bolster dry prose, but if nothing interesting has been said or done by chapter 3 you’ll be hard pressed to read anything further.
If it starts interesting then has a dry patch there’s at least that promise of things to come, a precedence set by that rich opening that adds color to the dry spell. Or if the use of language is a delight to read in itself you can get away with writing about nearly anything, for a while at least. If there’s neither, though, that’s just an open invitation to find something better to read.
Above all else a good beginning should strive to demonstrate that the main character and premise can and will be entertaining.