If you're looking for a clean, simple place to spend a night or two while exploring Luxembourg, then this hostel won't disappoint you. It's possibly the best hostel I've stayed at, mostly because of the extensive renovations that have been done (and are still being completed) recently. The afternoon/evening front desk guy, Jean-Marc, is super-friendly and speaks perfect English. It's especially nice to meet someone with a personality when you arrive in a new city on your own. The rooms are seriously brand-new and spotless--I had a 4-bed female room, with separate toilet and shower rooms within our suite for 19.30 euros per night (with breakfast) as a non-HI member. Linens and duvets are provided, and the bunk beds are really comfortable. Best of all, they don't squeak or shake when the person above you or below you changes positions during the night! It's an important quality for any frequent hostel-visitor.
Downstairs, the hostel offers a bar that serves lunch and dinner and drinks/snacks. Check the hostel website (www.youthhostels.lu) for weekly menus and opening hours. A great place for a coffee or to pick up some fruit to take with you during the day. There is also a really nice terrace outside that I found to be a perfect place to read and meet people.
The hostel has obviously made an effort to conserve energy in their timed lighting systems and water faucets that shut off automatically after about 10 seconds (this is actually perfect-- better than the faucets you have to hold down the whole time). Commendable and convenient.
Once you achieve a good shower temperature, it's great, so you shouldn't have to worry about cold shower water. Breakfast is basic but filling, with typical bread, cereal, cheese, meats, jams, applesauce, coffee, etc. The breakfast room is big, and I enjoyed picking up bits and pieces of lots of different languages.
The only drawback to the hostel is the steep path you have to take to get to it. Although their website suggests taking the #9 bus from the train station, I just picked up a map from the tourist office (which shows the hostel location), walked to the centre city, crossed the big Montee de Clausen bridge and followed the "Auberge de Jeunesse" sign turning left down a path that leads to rue Fort Olisy and the hostel. It's not really that hard, but the path would be a little challenging with huge bags or if the weather was especially wet. The hostel does offer a shuttle service to the train station for 2 euros per person, so you can always contact them and arrange transportation before your arrival.
Overall, this hostel is excellent and would be perfect for budget travellers of every age and motivation. See the website for further details in English.