When I have to schedule a 4:15 am wakeup call for myself, I pray that my shuttle is on time. Not late, not early, on time. No one wants wasted time at that ungodly hour of the morning. While SuperShuttle was 5-10 minutes early, I tried my best to rush my sleep-deprived body downstairs to avoid making the other passengers wait.
Notes about Super Shuttle:
1) Booking online is a total cinch - and you can pay online! Anddddd...you can add gratuity. This is great for those people, like myself, who rarely carry cash.
2) The online available times for pickup are roughly 2-3 hours before your flight. I understand the purpose for ensuring that passengers get to the airport in advance of their flight, but I was there more than 2 hours before my flight. And damn, that's early.
3) 10 minute automatic "Super Shuttle" is on its way before the driver gets to your destination. This is critical when it's 4-5 am.
I'll certainly use Super Shuttle again...but I'll keep in mind that the shuttle will likely be early...especially if it's an uber early pickup!