Don't feel there's too much point in complaining as a hostel's a hostel but there are a few things I'd like to point out.
Instead of using keycards the Sunflower hostel has a single key per room system in use which is outdated and can present issues when you need to get to the room but someone else has left with it, meaning you have to travel to reception and beg for a spare. On my first night of arrival I had to do this and this leads on to the second complaint I'd like to mention - the rude staff. Both of the men behind the bar ignored me to talk to each other for quite some time while I was trying to organise a key for my room, and this was a very off putting experience as I'd been travelling all day and just wanted to go to my bed. After telling one of the particularly difficult staff members (the bald guy, for lack of better description) several times that there was literally no way I could get into the room he finally accepted that he'd have to give me a spare but the fact that he felt the need to be so mean to me and made it seem like the whole key loss scenario was somehow my own fault was incredibly off putting as I just don't see the need for such nastiness in general. I'd also like to add that this particular complaint only really applies to the two older men (again, sorry for the lack of better description) who work there as everyone else seemed pleasant enough.
On a brighter note the €3 breakfast is a good bargain and the kitchen area/showers are excellent!