The apartment was beautiful inside, we were pleasantly surprised at how much space there was. Perfect for 2 of us but plenty of space for another couple of people. We had everything we needed during our stay and didn't really have any problems.
The noise from the street in the morning was a slight issue, as mentioned in other reviews, but we just played some white noise on our phones which helped.
Check in was fairly straightforward with the instructions we were given, but I would advise make sure you study them before you go in, because if you make the honest mistake like I did of locking the front door behind you (God forbid..) the security guard will show no mercy and will scream at you in Czech, which I didn't understand, but by the look on his face I'm pretty sure he wasn't saying "welcome to Prague".
Otherwise a very pleasant stay :)