My toddler has several paris of slip ons and he never complains about them. We don't let him wear them all the time or for long outings, but they seem comfy enough.
DD had some awhile back, but they were incredibly hard to get on for some reason. I felt like she had high arches or something (but she's actually quite flat-footed). And ditto the PP who said the arch support is bad--it is.
We do; they don't look comfy and DD would pick her Princess shoes over them any day. I think they have cute designs esp for boys. DH really likes that skateboarder look
Re: Vans - anyone's DC have them?