Reviewing Horton Hears A Who, Original 1970 Adaptation:

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Chuck Jones was an animator for Looney Tunes, and later an animation
director. About halfway into his career, he began to do two things:
become the caretaker of classic cartoons and bring them from theater to
television, as well as make more cartoons...

...and bring stories from books to animation. He did this with Dr.
Seuss, and was very successful with How The Grinch Stole Christmas.
Chuck Jones went crazy with The Grinch, making him truly diabolical
with his facial expressions and very crooked teeth. The choice of songs
was great, and they blended in perfectly without being annoying.

Chuck Jones returns four years later to produce Horton Hears A Who. I
don't know why it wasn't made in 1967 or sometime earlier. I am
guessing that Chuck Jones was too busy making The Bear That Wasn't (a
book) and a film about The Phantom Tollbooth (another book) ....if
Chuck Jones took a little time to make a Dr. Seuss special each year,
there would have been more of them made. Horton Hears A Who was the
last Dr. Seuss special to be made by Chuck Jones, as his distributor
MGM shut down the production. A sequel, which I have dubbed "Dr. Whoovy
Hears A Who!" remained unfinished and unreleased. Also very
interesting, is that Eugene Poddany is the music composer. Chuck
Jones's main music composer had been Dean Elliott ever since 1965, and
yet Eugene Poddany did the music and was scheduled to do the music for
Dr. Whoovy Hears A Who, and also wrote songs for "The Cat In The Hat
Song Book".

By the 1970s, the music was much more similar to Dean Elliott, so he
became the music composer for several years beginning with The Cat In
The Hat, which production started at MGM but ended up being finished by
DFE Films And after that, DFE became the producer for many years.
After detailed observation of the credits of these specials, it appears
that Chuck Jones was invited back to co-produce them with more freedom
than he had with The Cat In The Hat, but he declined...and instead
worked on books from George Selden and Rudyard Kipling. (A Very Merry
Cricket, Rikki-Tikki-Tavi, etc) If you are familiar with Chuck Jones,
you can see some of his production styles in this Dr. Seuss special,
which often clash with Dr. Seuss's.

Also, the music is by Eugene Poddany. He
does not do well in this special. He did much better in How The Grinch
Stole Christmas, but the music in Horton Hears A Who is almost
non-existent. This is the biggest, and perhaps the only, problem with
the special. It really makes it outdated. At the same time, I gave this
a ten star rating. It deserves to be treasured forever, and not simply
boxed with How The Grinch Stole Christmas. As for the picture quality,
it is excellent. They did a great job with shading and mixing all the
ink and paint. (and at the same time...Filmation is regarded as a
budget trimming production company, but they are NOT the only ones.
Chuck Jones did the same thing...with reusing the same segments again
and again, even from How The Grinch Stole Christmas!!) ....DFE did the
same thing when it came to trimming budgets...they did a lot of panning
and zooming.

AND it shows. In the credits, there isn't much more production staff in
a TV special of that era than there is in a theatrical cartoon short in
that era. This means that they used less production staff. Less
animators, and also fewer voice actors (they sang also) We get to see
Hans Conreid as the narrator for Horton Hears A Who. He also narrated
Dr. Seuss On The Loose and Halloween Is Grinch Night. (Hans Conreid is
also the voice of Horton, and in Halloween Is Grinch Night he is The
Grinch) ...in later specials, there is Allen Sherman as The Cat In The
Hat, Bob Holt as various people, and in almost every Dr. Seuss story
there is Thurl Ravenscroft as one of the singers.

Interestingly enough, June Foray was a voice actor for Dr. Seuss
cartoons but left when Chuck Jones did.

What is this cartoon about, and how well did they tell it? It is about
an elephant, on a tropical island. He was hot so he decided to cool off
in a "pool" (river/lake) A dust speck is caught in the wind, and
Horton's giant ears  hears a cry for
help. Horton saves them from drowning in the water and puts them on a
pink dandelion. There is a microscopic civilization in a dust speck,
who are unable to travel past their thick atmosphere. Dr. Whoovy,
professor of Science is able to communicate with the outside
world...barely. If it had not been for Horton's giant ears they all
would have died because nobody could hear them.

Jane Kangaroo and her son don't see how anybody could live inside the
dust speck. She says she doesn't hear any voices, and that Horton
doesn't either. She has a pair of magnifying glasses, which could not
detect any people. They believe that Horton is crazy (and always has
been) and has just now "flipped his lid" and something must be done
before becoming dangerous. They get a second opinion from Misses
Toucanella, who agrees and they warn everybody. Rumors grow and grow
about Horton's insanity. The birds don't try to harm Horton or the dust
speck. Instead, they flee.

Jane on the other hand, consults The Wikersham family, who are a bunch
of  lemurs. and a "Black-Bottomed Bird" who want
to grab and destroy the dust speck.

At the same time, Dr. Hoovey has to deal with his own group of
non-believers. Almost all of them dismiss him from being reputable.
They start singing and mocking Dr. Whoovey and the song is hilarious.
There is a character with a very high pitched voice asking What an
elephant is.

They change their minds once The Black Bottomed Bird drops the
dandelion with the dust speck on it. He believes it has been destroyed
and can't be found, and unknowingly almost kills them. Horton follows
and picks EVERY filled of flowers, and three billion flowers later

anyways...Horton finds them and they survived the crash. the Whos in
Whoville, (A name that Dr. Seuss gives to every person that he does not
want to name, as this is also been done in How The Grinch Stole
Christmas) now believe that whenever Dr. Whooveey says disaster will
happen, it will indeed happen.

They other people of the jungle decided to fry the dust speck and the
clover flower that it sits on, and they tie and lock up Horton,
believing he is dangerous and a radical politician. The Whos decide to
make as much noise as possible to get through the atmosphere and then
Dr. Whooovey finds JoJo, who makes a small but sufficient noise to make
the sounds more louder and easily heard.

This is where it gets very silly. The angry rioters that were probably
going to cook and eat Horton after they cooked the dust speck and
flower, are now able to hear the Whos. They are VERY quickly calmed
down and now say "They ARE There...AwwWwWwww How Cute!! Tiny People!!!!
We have to tell the news about this!! Let's try to pet the tiny
people!!" No apologies to Horton, but they do throw a parade at the
request and direction of Jane. And the frightened birds all came back
to admire the Whos. They drop Horton off at home, and then they don't
bother Horton or the Whos after that.

To make things even crazier, Dr. Hooovieee stumbles onto his own dust
speck, which is crying out for help. He catches it, but then becomes
very afraid of it. This is what MOST LIKELY ended up being the plot
device for the unreleased sequel.