Great plant choice!

It looks like the brown stem parts are last year’s growth and the green branches are this year’s stems.

As far as the brown spots on the leaves, they could be a slight fungal infection from overhead watering either in your garden or previously at the nursery or more probably mechanical damage that happened when moving it to your house and then planting it. The lack of perkiness is that it is a new planting and the plant is still settling in and growing new roots, so it is a bit stressed, especially with the recent hot weather in many parts of the US. If it needs it, give it some temporary shade on hot days, such as a lawn chair placed to the SW of the plant where its shadow will reduce light levels during the hottest part of the day. Keep an eye on soil moisture, letting it get to just lightly moist before giving it a long slow deep watering that soaks the soil to 8” or more. If the limp branches don’t perk up overnight, then come back and let us know, but that isn’t unusual to see in a first year planting in hot weather.