Marcela's place is very clean--it feels lived in, but is clean. The location is great and accessible to the center of town. Others have mentioned the street can be noisy. If you come from a big city, you'll understand. Since there is no air conditioning, keeping the window open allows in the noise. I had earplugs with me and that was fine.
Marcela keeps lots of stuff in the apartment like a fan, dryer, electric tea kettle and plenty of kitchenware, which was super helpful. She also stocks new toiletries in the bathroom. She even has maps if you need resources for the city.
I wish I was able to speak Czech and communicate with Marcela, but check-in and out was easy enough regardless, and Marcela seems very kind--I'm sure she'd be happy to help if you needed anything during your stay, but also isn't in your way at all.
This place is a really great find in Prague!