I’m a Cadet right now and will commission into the Reserves. What is it like?

get ready to be tossed around by your CO for a while but then it will get better. Stand your ground with senior ncos.

That's a big and open ended question. What branch are you interested? Army Reserve or Army National Guard? What are you looking to get out of it and how much are you willing to invest.
My last Active Reserve time was with a Kentucky Army National Guard Combat Engineer Unit. As a senior lieutenant and captain, I averaged about 80 days a year between schools, unit duty and annual training, plus the one weekend a month. The battalion was usually supporting a Civil Action Program in Central or South America (road or school building usually) and we did Domestic Action Programs for the State on a regular basis also. Being an Engineer unit, we were first to get tapped for Fire Duty, Flood Duty, Snow Emergencies or similar disasters in the State too. Since I left and after 2001, both of the line units I served have done a couple of deployments to the Balkans and to Iraq, although that seems to have died down for now. My point being that it can be a time consuming and demanding job at command levels and it's often hard to find a civilian employer that understands you being gone a 1/4 of the year. I could have spent more time on duty if I had wanted and we normally had a full time position or two available on one of the CAP Missions.
OTOH, don't get me wrong that I didn't like it. I enjoyed the challenge of being an Engineer Officer, in a Divisional Combat Engineering Unit at the time the platoon leader was often the Task Force Engineer as well as being the Platoon leader, the job is fast paced and you get to do a lot of different things. Engineer Company Commander was the best job I had in the Army.

Like a box of chocolates, you never know what you're going to get....