After staying at some awful hostels, I was pleasantly surprised to find that CALM exceeded my expectations. This is very close to the bus/train station so no trouble getting to and from the hostel.
Check-in was also very friendly, accommodating, and a pleasant experience. The front desk staff are of course French, but speak English as well. I know a little French, but the staff were able to communicate to me in both languages effectively and kindly, which meant a lot since I was traveling alone.
The bedspace itself (I was in the all girls suite) was quite nice and offered a lot of privacy and access to ports for charging. I also had access to a spacious, provided locker. The bathroom and kitchen area were always clean, and there was a very young vibe to the place which I loved.
Lille is generally a safe city, which is great since I was traveling alone. That being said, the location is near some 'not-nice' locations and can be poorly lit at night. If you are a woman traveling alone (as I was), I would recommend to be aware and vigilant as always.
Would definitely stay here again!