(Today's passage covers Samuel's birth and his dedication to God, the wickedness of Eli's sons, and Samuel's call to God.)
The first three chapters of Samuel are a study in contrasts between Samuel, the commoner child dedicated at birth to serve God, and the sons of Eli, the high priest, Hophni and Phinehas (yes, another Phinehas).
Samuel, from the moment of his birth, is a man of God. His mother, Hannah, is one of the many barren Biblical women, following in the footsteps of Sarah and Rachel. She prays fervently and vows that if God gives her a son, she will dedicate him to His service. Furthermore, he will be a Nazarite, like Samson. (1 Sam. 1:11) As we might expect, God remembers Hannah and grants her a son, whom she names Samuel. True to her word, she brings him to the temple, where he ministers to God.
Even though Samson is from a non-Levite family (his father was from Ephraim), everyone likes him. He finds favour both with God and with his fellow men. (1 Sam. 2:26) Though he's still a child at this point in the narrative, it seems that he is everything one could hope for in a boy: obedient, loyal, God-fearing, and friendly.
Contrast him with the two priestly sons, Hophni and Phinehas. These two men are wicked. Despite being ordained priests, they don't worship God, and they have earned the ire of their fellow men. Among their crimes, they try to gain more than their fair portion of the sacrificial meat (1 Sam. 2:12-17) and sleep with many of their congregants. (1 Sam. 2:22-25) They threaten physical violence when they don't get their way (1 Sam. 2:16), and just generally seem like nasty people.
They're so bad, in fact, that God curses Eli: he tells him that all his descendants will die young, in the prime of their lives, and that both his sons will die in a single day. The priesthood will pass to someone worthy, and Eli's family will beg before him to have enough food to eat. (1 Sam. 2:27-36)
Obviously, these chapters are a warning against inherited power. The sons of Eli, the ordained priests, are wicked and corrupt. Samuel, a commoner, has a pure, good heart. Eventually, everyone in Israel knows that Samuel is a prophet (1 Sam. 3:20), while God is on the verge of destroying Eli's family. In the Bible, worth is rarely determined by lineage but by deeds. The book of Genesis had a knack for favouring younger sons over their elder brothers. Gideon, the mighty warrior from Judg. 6, was a nobody from Manasseh. Now, again we have a worthy man from a common background, who is raised up to be a prophet for the entirety of Israel.
In this, as in many things, the Hebrews were ahead of their times. Unfortunately, they didn't listen to the warning, and fell back into the trap of inherited power over and over again, just like everyone else.