Just as a lily placed among thorns is difficult for its owner to pluck, so was the deliverance of Israel difficult for the Holy One...
When I think of the emotional response to the Jews crossing the Red Sea and the Egyptians drowning, I think of a popular midrash. The angels are rejoicing, singing, and praising G-d following the Israelites' successful crossing through the water. G-d quiets the angels and reminds them that the Egyptians - also created in G-d's image - are drowning, and this is nothing to rejoice over (Talmud Tractate Megillah 10b).
Aggados 1:5:1-2 offer imagery that compliments the above midrash, and illustrates the difficulty of the situation for G-d who had to remove "a nation from the midst of a nation." But I want to see something about the people's response.
In Exodus 15:1-18 we're shown the song the Israelites sang after surviving the crossing of the Red Sea. We have an action or two: singing and rejoicing, mimicking that of the angels. But if the angels were admonished for their joyous reaction, did the people also have a change of heart? Or perhaps feel something that wasn't revealed in Exodus?
The Israelites had just escaped, they were tired. It was a rough crossing both physically and emotionally (having to put that much faith in a G-d you're not necessarily accustom to, or intimate with, yet). They were free, sure, and the crossing was a success, but you're in a foreign desert without any of the structure and customs you were familiar with. And you're about to spend forty years wandering. So though they sang at the sea, and should have been happy, I'm sure many of the Israelites were thinking of the wonder around them... and wanted to take a moment to focus on the mud between their toes before they were "replanted" in their new lives as a free nation.