Here are some things I likeabout online check-in:
1) Your credit card info is entered directly into the Disney resort system, no need to present it at the front desk. That kind of adds an extra layer of security in this economy, as the front desk staff can not access the number directly.
2) If you enter a phone number where you can be reached, an automated system will notify you that your room is ready and the number, even before you arrive at the resort. I was at a toll booth on the turnpike when my OnStar rang, it was a computer voice letting my know that my room was waiting for me, and the room number.
3) You do save a little time, as the keys are printed and waiting, you just have to sign the Credit Card slip and get your car pass.
What I don't particularly like about online check-in:
1) Again, the room is pre-assigned, so if I don't like the location, I need to inform the desk when we arrive to be reassigned, if anything is available. When we didn;t do online check-in, we were normally given our choice of several general locations under "room ready" at OKW. This is a give and take, as locations are subjective, and most of the time the pre-asigned room will be fine.
2) With online check-in there, so far, no way to designate which cards have charging privledges. If you are traveling in a mixed group, you need to have the room card re-printed.
Overall, for us, online check-in works well. For others, it may not be the best option.