It was a big deal, because "the word of the LORD was rare in those days; there was no frequent vision." Most of the time when people read this passage they discuss the ways we should be more open to hearing God. Others will say we should develop more of a child-like faith.
However, Walter Brueggemann points out the following.
The roles between [Eli and Samuel] are then reversed (vv.15-18) Eli has forfieted the word of Yahweh, and it is given to Samuel. Eli is now dependent upon Samuel to learn the word of Yahweh. Earlier, Samuel is uncertain and must be guided. Now he confidently receives the oracle but is reluctant to tell Eli, because the oracle is against Eli (vv. 15-18). It is surely intentional irony that in verse 16 Samuel makes the same response to Eli that he does in the earlier text, ' Here am I.' While the response is the same and Samuel's deference to Eli is consistent, there is no doubt that the power has shifted. The young innocent one is now authorized; the old knowing one has become fully dependent upon Samuel. The reversal of roles is not stated directly, but the narrative is formed so that the point becomes unavoidable. Yahweh does indeed 'raise up and bring down'.I believe that point is as important to remember as the others. We're not entitled to anything. We're not in control. God is.
Brueggemann, Walter. Interpretations: First and Second Samuel. Louisville. John Knox Press, 1990. p.25