I also booked an Easy Bus from home for my arrival in Paris. My booking was for noon. I followed the directions on where to meet them but no bus (and no signage to make me think there might be a bus). I asked at an information desk and they said they run roughly every 45 minutes. I didn't want to wait around to see when they might show up, then take an hour to get downtown. The Easy Bus website also stated specifically that your booking was only for the trip you booked. You could use your ticket for another bus within an hour of your planned arrival on a space available basis.
I decided to write off the 2 euros I had spent for the booking and instead take the RER/metro into town (10 euro). The RER is faster anyway. It gets you downtown in about 45 minutes while a bus, shuttle or taxi will take better than an hour.
I travel carry-on only. This trip I had under 20 lbs in a daypack for my 18 day trip. In the future, I'll just plan to take RER. I'd only take a taxi if I had luggage that would make public transportation difficult.