I bought this azalea a few weeks ago. It looked really cool when yhe flowers were on it. But im wondering if this will fill out in time or will it stay stalky?
Hard to tell. It is showing signs of new growth at the base, but the long bare parts are unlikely to put out any unless they are pruned back. Leaves and flowers at the tip of branches is a natural growth pattern for many deciduous azaleas. Once planted out, this one looks as if it will spread through new branches emerging from the base.
Should I prune back the branches?
Your choice. Pruned back to the level of the lower growth and planted in an area that receives at least full morning sun, it will look less odd than it does with areas of bare stems.
It's like a gawky teenager hyped on sugar (fertilizer) It will fill in as it gets larger.
Here's one of my deciduous azaleas.