Overall, we had a great stay at Omega Guesthouse. The front-desk staff were very friendly, and the location was perfect - right next to a metro and tram stop as well as a Lidl, in the city centre, so it was easy to get around. The bedroom, bathroom, and shared kitchen were clean. It was also nice and quiet, except for people coming through the main door into the kitchen area (which we were next to, so could have been just our room). We paid for the AC, which was 2 euros a night (approximately), which DID work well, so worth paying for.
We did have a couple of issues during our stay. One, there was only one curtain on the curtain rail, not two, so we couldn't block out the whole window, and since we were on the ground floor looking into the communal space, it meant people could see into the room if they wanted to. Secondly, there was a bit of an insect problem, with mosquitoes in the room (although there's not much they could do about that I guess), and we came back one night to quite a few roaches or beetles (it was dark so couldn't quite see) in the communal courtyard. They did have exterminators around one of the days (for which we weren't given any forewarning until they were at our door).
Overall, for the price, it was a great place to stay for the location alone. Plus, despite the minor issues, overall we found it to be very clean and comfortable. We would come back to stay (but maybe ask for a different room). Thanks for a great stay!