What is it about classical that is most enjoyable... The structure of the piece... The complexity and beauty of the different instruments?
Classical is more complex, more sophisticated than popular music. The sophistication is primarily harmonic, which allows more intense emotional development. More dopamine, the hormone that makes life worth living.
Is it sometimes an acquired taste and, if so, how did you go about acquiring it.
Everything is an acquired taste. Music listening is a skill. Popular music takes advantage of the skills you already have and does not challenge the listener at all. Well that's not true, most pop is deprave and challenges you to accept new negative thoughts that bring your consciousness down. It's designed to slip right in unnoticed, to overcome your resistance to the depravity, and tickle your funny bone, give you the beat, appeal to your animal instincts, maybe plant a few subliminal negative messages, but no higher order comprehension required. Other genres deliberately challenge your listening skills, your musical sophistication, you knowledge, your tolerance of dissonance, your ability and willingness to have a dopamine response (strong and meaningful emotional experience.) So with genres other than pop you have to learn to listen to it, it has to grow on you. Like any genre, classical offers easy music to start off with, and this leads you to harder material that offers more intense experience when you are ready. That's how I look at it. There are many classical works written to appeal to popular music listening skill. Mozart wrote what later came to be known as "twinkle twinkle little star," etc. A few pieces from 1800s became pop hits in 1970s with little change. But Bartok and Schoenberg never had any hits. Most beginners will really hate their music. But it grows once you have been introduced gently by Dvorak to the concepts that they dive very deeply into like dissonant or atonal composition. People reject music because it forces your mind to open to ideas and feeling you don't want to experience.
If you didn't enjoy it at first, did you keep at it so to speak and begin enjoying it over time?
Forcing yourself to listen to hard music will not be successful. You are only practicing rejecting it. To grow as a listener, you should listen to music you like, but avoid boredom. If you want to add classical music to your listening repertoir, you need to find classical music that appeals to you, and wear it out. When you wear out music, or get bored of it, that means you are craving something more powerful, and classical can supply what you crave. The next thing will come along. You'll hear it on the radio, or read about it. Over time your listening skill and craving for musical intensity and the feelings it brings will increase. When I started listening to classical I discovered new composers and stuck with them until I got it, then another would come along and I'd go off with them. I still return to the others to dig deeper, but the big treasures are easy to find. Once you've found 10 treasures by Dvorak you are getting into the weeds and might start hearing the "house sound." If you have a deep spiritual connection to his music it will last longer, but otherwise you'll move on, seeking deeper more powerful music. You'll start to sense there is a treasure inside yourself that you are digging for and the music is the shovel.
Sometimes the problem is that pop music has weakened you. It gives you everything, like a $20 hooker. Let's get this over with. Here's the beat now move! Here's some ear candy, now smile! Here's some sex lyrics, get horny! It is the music of the masses, the masses love to be massed, and corralled into the same conformitive thought and feeling. If you've only ever listened to pop, you may feel uncomfortable breaking off from the herd and flying on your own without max headroom telling you what to think and what to feel. The best way to cleanup a teenage loitering spot is to play classical music there. But use bulletproof speakers. It forces them to expand their mind which prevents herd/gang/crowd think, forces them to be individuals. This is why you don't have fights drugs and rape at music concerts playing music for individuals.
If you didn't enjoy a piece, what was it that was lacking?
It is lacking a fertile mind for the musical seed to take root. I swear at it and change to the pop station.
I am curious Rich why you loved the first 20 minutes and didn't care for the rest.
Because it is too long for my tolerance. Bach is a unique sound. All Bach music sounds similar in melody, harmony, and structure. Once you've heard a little, you got it. Whether you want more is a spiritual matter. It is as easy as pop to absorb, it just slips right in. But most people can't listen to that much Bach because it calls forth the deepest spiritual feelings possible from your current level of spiritual development. It has extremely intense harmony, very simple and pure which penetrates deeply into your soul. There is no music more musical than Bach. Some listeners are not ready or willing to open so deeply to the rays of heaven. But some are born with supernatural ability to listen to it without limit. Whoever commissioned St. Matthews Passion was one such superman, or got taken, we'll never know. I find it pretty easy to listen to Bach's tempo music, it has a beat, strong structure, it's a little music machine in bite sized chunks. Some of it is just exercises he wrote for his keyboard students. But it all has the Bach magic. But that is a small part of his canon. Most of what he wrote was church music, something new every Sunday for 3 decades? Most of it was choral music. St. Matthews Passion is mostly choral songs, lots of solo singers. It's kind of like a opera before opera got big. The singers sing simple Bach melodies over and over for hours. The music stops, starts, space and pause like an opera. It's not like his English Suites for Harpsichord that is a teletype machine pumping out intense melody and harmony for easy consumption. Unless you follow along with the story, understand German, it can be difficult to take that stop/start singing of the same sound over and over for 2 hours, no intermission. For 20 minutes it is new, and it sounds beautiful.
I am just trying to understand classical on a much deeper level
You can try to imagine it, to mentally process your current information into an illusion of understanding about something you've not fully experienced. But you'll find it difficult to imagine it accurately, so you'll be forced to make assumptions which leads to prejudice. To know classical music you have to jump in and do it. Find some classical works that you enjoy to listen to, then consume them over and over until you are bored. Then something new will come along, rinse, repeat.
In the past we have done threads about appropriate music for a beginner to start listening to a new genre, to get them hooked. I need to start one for rock, but it might be a good time for another classical thread like that.