Did they see it as the end of the Reich? War? Were they sad?
This is hardly an all-encompassing answer, but Omer Bartov's Hitller's Army had a few good passages taken from German soldiers' memoirs showing their reaction to Hitler's suicide. These were part of his broader point of the "indoctrination" of the common soldier to be loyal to Hitler and to believe the Nazi party propaganda regarding the motives of the Soviet Union.
Bartov first notes that most of the Wehrmacht's combat troops spent their formative years under National Socialism and its indoctrination programs (Hitler Youth, etc.). Given the programs of indoctrination, Bartov argues "there is little doubt that the youths who were to become the Wehrmacht's combat troops were to a large extent molded in the spirit of Nazism, and prepared for the kind of war the regime was determined to wage" (p. 109).
Dieter Borkoski, a sixteen year old fighting in Berlin, wrote later that hearing "these words make me feel sick, as if I would have to vomit. I think that my life has no sense any more. What was this battle for, what were the deaths of so many people for? Life has apparently become worthless, for if Hitler has shot himself, the Russians will have finally won....Has the Fuhrer not betrayed his Volk then after all?" (p. 110). This shows an interesting mix in the mindset of a very young soldier - the belief in the demigod like image of Hitler as the only hope of Germany, but also an acceptance of the broader Nazi ideology regarding the need for a "preemptive attack" on the Soviet Union because of their designs on Germany.
Not all were as fatalistic, and continued to feel a sense of mission after Hitler's death. Bartov points to the memoir of German pilot Hans-Ulrich Rudel, published years after the wars end in 1952, as proof of the acceptance of broad strokes of Nazi doctrine by the common German soldier. Rudel wrote that although Hitler's suicide "had a stunning effect upon the troops...the Red hordes are devastating our country...we must fight on. We shall only lay down our arms when our leaders give the order...it is our plain duty also to destiny which has placed us geographically in the heart of Europe and which we have obeyed for centuries: to be the bulwark of Europe against the East. Whether or not Europe understands or likes the role which fate has thrust upon us, or whether her attitude is one of fatal indifference or even of hostility, does not alter by one iota our European duty" (p. 139).