It stayed cool inside, even during very warm days, and I had no issues working with the Wi-Fi. The kitchen has all the basics for actual cooking (a good selection of pots and pans) but it's missing some smaller everyday utensils (like a bottle opener or vegetable peeler). You can definitely make a meal, just check the drawers before you start!
Zsuzsanna is also a great host, always responsive and helpful. She even accommodated a very late check-in (1 AM) with no complaints. Would definitely recommend her and the place for your stay in Budapest!