What can we learn from Yisro's words, "Baruch Hashem"?
Berachos 54a: It teaches us the obligation to recite a Berachah over a miracle. 1
Sanhedrin 94a: It is an embarrassment that Yisrael themselves did not bless Hashem, until Yisro came and said "Baruch Hashem." 2
The Gemara (Sanhedrin 94a) remarks, that it was a disgrace for Yisrael that they did not say "Baruch Hashem" [over their Redemption], until Yisro came along and did so. Why indeed hadn't Bnei Yisrael used this term previously?
Maharal (Netzach Yisrael Ch. 43, p. 176): It wasn't that Bnei Yisrael were unwilling to utter this phrase, but rather that it was not yet fitting that they do so. Although they had left the bondage of Egypt, they had not yet attained 'Berachah' - which means something additional or extra. 1 Yisro, on the other hand, had not been in bondage at all! He came and added himself onto Yisrael, 2 out of his love for them; and that is considered 'Berachah.' 3
Maharal (Chidushei Agados Vol. 3, p. 192, to Sanhedrin 94a): Yisrael was redeemed in the merit of the Avos, and the merit of the Bris. Their Redemption came in the realm of Din -- not as a Berachah or extra favor. In a similar vein, Yisrael numbered 600,000 at that time - i.e. they had reached a state of completion, without any surplus; that is when they were worthy of Redemption. (See Maharal Gevuros Hashem Ch. 3, p. 26; refer to 12:37:1.3:1 and its notes.) To attain surplus and Berachah, they had to exceed that number; it was therefore Yisro, who joined them, who was the first one to bless Hashem.
As above (18:1:2.4:1 ) - Yisro did not nullify himself among Yisrael; rather, he added himself on to them.
Nevertheless, the Gemara tells us that it was still a bit disgraceful for Yisrael that they did not have this trait among themselves. Maharal Chidushei Agados (ibid.) - Yisrael should have reached this level, and this number, on their own.
To whom does "Eschem" refer?
Ramban: It refers to Moshe and Yisrael.
Rashbam and Seforno: It refers to Moshe and Aharon.
Oznayim la'Torah: It refers to Moshe, Aharon, and the elders who accompanied Moshe and Aharon to greet Yisro.
What was Yisro referring to when he mentioned, "from the hand of Egypt" and "from the hand of Pharaoh;" and then added, "and from under the hand of Egypt"?
Rashi: He was referring to the fact that, not only did Hashem save Yisrael from Egypt (a tough nation), and from Pharaoh (a tough king), but He also rescued them from a particularly harsh subjugation to which they were subjected.
Ramban #1: He was referring to two independent miracles - 1. to saving Yisrael from the hands of the angry Egyptians (after each plague), and Moshe from the clutches of Pharaoh whenever he came to warn him; 1 2. to the rescue of Yisrael from the subjugation of Egypt and taking them out to freedom.
Ramban #2 (citing the Ibn Ezra), Seforno and Rashbam: As above, but "Eschem" refers to both to Moshe and Aharon, whom Hashem rescued especially from the clutches of the Egyptians and Pharaoh.
Oznayim la'Torah: Yisro said, "Asher Hitzil Eschem mi'Yad Mitzrayim u'mi'Yad Pharaoh" - from the leadership of such cruel masters, which the elite of Yisrael 2 resented; and "Hitzil Es ha'Am mi'Tachas Yad Mitzrayim" - from the harsh conditions of the slavery, which all the people suffered. Yisro now blessed Hashem for both salvations.
Why did Yisro mention "mi'Yad Pharaoh;" and not "mi'Yad Amalek"?
Oznayim la'Torah: Yisro was afraid that, since Yehoshua had only weakened Amalek and not destroyed them completely (as opposed to Mitzrayim, whose every soldier was drowned in the Yam-Suf), if they would hear that he was happy about their downfall, they would take revenge. 1
See Oznayim la'Torah for another (similar) answer.
QUESTIONS ON RASHI
Rashi writes: "'Mi'Tachas Yad Mitzrayim' (lit. 'from under the hand of Egypt') - As per Targum, [a 'heavy hand' is] an expression of domineering and subjugation ... i.e., their slave-labor." What is Rashi coming to clarify?
Gur Aryeh: Unlike the phrase "Yad Mitzrayim" in the preceding Pasuk (18:9), which simply means their domain or authority, the phrase "Tachas Yad" (under their hand) in this Pasuk means salvation from their heavy-handed rule.
