Unfortunately I did not end up staying at Jaroslav's place. Some thoughts--
Interaction: Jaroslav was not able to meet me to give the key, though left it at a local cafe. The instructions listed inside the envelope were very detailed. Jaroslav was also very quick at responding to text messages. Although a con about leaving the envelope in a cafe is the location of the cafe. We arrived to Prague later in the evening when it was dark and the cafe was difficult to locate. I ended up walking in and out of numerous buildings and kept getting pointed in different locations until I finally found the cafe where the key was.
Building: Cute, quiet location. Building has 1 main entrance plus 2 other doors you have to unlock until you finally are able to go inside apartment. Toilet and shower are separate.
Cleanliness: This is the reason we cancelled our stay. The apartment looked like no one's lived there for a while, very untouched, but the amount of cobwebs and spiders all over the ceilings and walls were ridiculous...My husband and I ended up booking a hotel. Jaroslav offered to come clean the apartment but you can't unsee what you've seen..I wouldn't of been able to sleep without thinking something's crawling all over me or in my suitcase...and the apartment needed a very good cleaning, one that would've taken longer than I would have wanted to wait on my vacation. After telling Jaroslav this he insisted that he checked out the apartment that day and it looked fine, which was dishonest in my opinion. The way the apartment looked-it hasn't been cleaned in months! I sense that it's a property that is just rented out by Jaroslav, not one that he actually lives in. Jaroslav mentioned that there are a lot of spiders due to the river...I wish I'd known this as a factor before booking..don't get me wrong, I go camping out in the woods quite often, bugs don't bother me like the average joe..but this was an infestation-best word to use. And they didn't look like they just accumulated over the course of a day. I think if a proper cleaning would have been done to get rid of the spiderwebs and spiders, situation would have been tolerable.
Side note: Beware of cab drivers scamming you. Was going to be charged 30 euros for a ride that was actually 3 euros from the train station (we used uber).