We stay at OKW frequently, and we were just there in January. We do take our car everywhere but MK, where it's better to take the bus because you skip the Ticket and Trasporation Center. Any time you take public transportation, you sometimes have to wait a bit if you've just missed the bus. That happened to us, and we did have to wait 15 minutes (saw the bus heading out of OKW just as we got to the stop!)
But I thought the bus service at OKW was better than I'd ever seen it. Buses seemed to be going through all the time. But folding up the stroller to get on a bus can be a drag, it's true. We have toddler, so we take the car most places.
One note: We stayed one night to see Wishes, and when we came out, saw the longest line for the OKW bus we'd ever seen! We thought it would take hours to get home. But they brought over 3 buses simultaneously to accommodate the big crowd. We were on in a jiffy.
Why don't you want to drive? Will you not have a car?