I love these sandals, but do they love me?

My birthday present. Running sandals. I took them out for a trial run today: Forty-nine degrees and muddy. My toes did get a bit cold and bloody—but the blood only because I stepped through some thorny undergrowth. The tread is quite flexible, so you can feel the rocks and roots. The right sandal was a little loose, but not enough for me to stop and try to figure out how to tighten it. The lacing pattern is slightly complex. They actually stayed in place well. I had already altered my gait so that I was landing more or less flat-footed, but the sandals require even more of a shift to the front. You pretty much have to land on the ball of your foot. After a short run of less than three miles my calves were aching. These things will take some getting used to.