Here’s a review that was published in Allentown’s Morning Call on April 20, 1968:

By DAN PEARSON
If one wandered through the crowd of 4,700 that jammed Muhlenberg College’s Memorial Hall last night to hear Paul Simon and Art Garfunkel, and if one culled every person over 35, it would have been difficult to field two football teams.
Simon and Garfunkel – folk- singers, philosophers and highly-paid vagabond of the concert stage are among the young gods worshipped with increasing fervor by America’s youth cult on and off campus.
Listening to the applause that hammers down like a summer cloudburst on a tin roof. It is easy to see how this talented duo has come to symbolize the impatience, social emancipation, and dissatisfaction with old standards of the nation’s youth.
Although their songs often carry the message of dissent, they are not brutally anti-establishment.
They have a facility or engaging in constructive mockery without evoking a torrent of outrage. It’s quite an unusual style that is all the more effective when applied in low key.
S & G, whose most successful recording is “The Sounds of Silence, are possessed of fine voices. But they are hardly superior vocally to many duos and trios in the recording and concert fields. Their one basic tone can best be described as soft hillbilly drawl that characterized much western music over the years. Neither are their voices particularly harmonious.
What sets these young performers far above the average folksinger out to make a fast buck, is their involvement in their material, a relaxed approach, and their undeniable professionalism.

Poor Acoustics
Muhlenberg’s Memorial Hall far from ideal as a concert hall, and Simon and Garfunkel were considerably hampered by poor acoustics that muffled their lyrics, blurred their melodies and took the edge off Simon’s exceptional virtuosity on the guitar.
Both performers had microphones, but very few of their remarks were understood at the rear of the spacious hall.
S & G gained much of their popularity making guest shots on network variety television shows.
Their albums have become top sellers and last year they provided most of
the musical soundtrack for the hit movie. “The Graduate.”

Poetry To Music
Among their selections last night – all well received – were “Mrs. Robinson.” “At the Zoo.” “Cloudy.” “Feeling Groovy.” If any two singers
can put poetry to music, they are Simon and Garfunkel.
A concert by this duo suffers, however. from a lack of varie- y in style and material. S & G make only a faint attempt a comedy. And even their anti- establishment jibes about the nightly police search of their car are accorded only courtesy laughter.
After the concert is 20 minutes old, one song tends to sound pretty much like the previous number, and the listener wonders whether a little theatrical staging of sorts wouldn’t help

Loud Response
By contrast, the Smothers Brothers presented a livelier and much more entertaining show two years ago in the same Hallby alternating slapstick and song, in a manner designed to keep the audience in a constant uproar. They had the theatrics. Yet it is difficult to believe that any performers ever received more spirited ap plause at Muhlenberg than S&G. The response was enough to shatter the eardrums.
No small part of the evening’s pleasure was the viewing of all the lovely young ladies in their colorful miniskirts and swirling hairdos. It was warm n the hall-the air conditioning machinery is too noisy for recitals-and the air inside was an exotic mixture of a hundred different perfume scents.
Two young couples arriving at the hall contributed shades of Bonnie and Clyde. The men in old-style fedoras and wide rousers raised many an eyebrow in amusement.

In another – shorter – review (published a week later) we learn that Art Garfunkel was frequently wandering to the back of the stage. It seems that he had been quite ill and throughout the evenening was under the care of a doctor.

Where were you 55 years ago on April 11th? I was in a recordshop and buying my first 45rpm:

Simon & Garfunkel’s El Condor Pasa / Why don’t your write me was a major hit in the Netherlands. I remember playing it 100times, it drove most of the family nuts. I was a fan and hooked to the music of this great duo.

Next singles were “Cecilia / So long, Frank Lloyd Wright“, “Bridge over troubled water / Keep the cyustomer satisfied“, “Mrs Robinson / Old Friends/Bookends” and “The Boxer / Baby Driver“.