The Threshold is a pretty good bow for a beginner. I believe the riser (handle) is cast vs machined aluminum for the rest of the lineup. Limbs, axles, strings/cables, cams, etc are either the same or of the same quality as the Gold series bows.
The accessories, although not the highest quality, will work well enough for you to begin with. Somewhere down the road you may desire to change something like the rest or the sight, but that is your choice. As you learn and see other accessories and talk with other people something might grab your fancy and you end up spending more money for them.
About the only thing you'll need more of is arrows. Maybe a release, too. I don't know if the kit comes with one.
Maybe a couple years down the road you'll even want a completely new outfit. This sport can become addictive, but have fun with whatever you choose.
If You're Not Living on the Edge You're Taking Up Too Much Space
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