It's not a little bit more comfortable, it's a lot more comfortable, and that's just the seat (which may even be a lie-flat allowing you to sleep). Add to that: much larger personal space; quieter environment (rarely any noisy children/babies; cabin farther from engines); better food; meal services that take longer to complete and thus helping the time pass; ability to work if you need to (can you really use a laptop in coach for any extended period?) priority check-in, baggage, boarding and lounge access (for those with no status), etc etc.

Taking for example a route I often fly, a coach ticket is 80K while a business ticket is 115-120K (varies by airline). So it's only a 50% permium, whereas the difference in price between Y and C is x3, if you were to purchase tickets. The additional 35-40K is well worth it to me for a 24-hour each-direction voyage. There's nothing like sleeping on a lie-flat on an 8-hour flight and then taking a hot shower in the lounge at FRA before continuing on.

I would not get an F ticket, that would be a waste to me because I perceive very little added value in F versus C, which will be especially true once all C has lie-flats.