It takes 10 minutes, you don't have to go through the city of Paris. You can and it's cheaper, but it takes about 1.5 hours.
I prefer the train over the bus. I hate the bus because there is a schedule but they don't adhere to it. When the bus arrives, already late or on time, then first the bus driver takes a break. There is always an issue with at least one person with tickets. I get frustrated with the inefficiency.
The downside of the train is, that it's hard to time it correctly with a flight. As the train times are irregular, and you have to build in possible flight delays.
Upside is, if you have to wait an hour at the train station, there are some shops and restaurants, you can sit down, recharge your phone, use the wifi.
Once schedules are published they shouldn't change. I have never experienced it.
You can book 3 months in advance, so they are now at releasing the fares for early January. But you can already see the planned schedule. If you are lucky, it can be cheaper than the bus.
https://en.oui.sncf/en/