Liking a hostel experience for a first-timer depends a lot on being prepared for what you're getting into. Whenever I've stayed with friends who are novice travellers or seen bad reviews from newbie hostellers for otherwise-great hostels, it has often been a case of them expecting something and then finding their preconceptions incorrect.
Hostelling gets a 'bad reputation' sometimes in the sense that people think only of crowded dorms with leaky roofs full of smelly backpackers (with smelly backpacks). You'll still find those, more often than not in countries outside what you'd consider the 'Western world' - simply because economics mostly dictate hostels in the 'Western world' need to charge a certain amount to exist as a viable business. I've stayed in my share of cheap-ass hostels with flimsy mattresses and one broken shower serving four floors of travellers... but chances are you'll only choose such a place once you have a little experience under your belt and deliberately want to save money.
In most cases, hostels are far more comfortable than a minimum 'roof over your head' scenario. Typical low / mid-range hostels these days offer clean showers and toilets and free Wi-Fi access at the very least. There's also a rising trend of 'boutique hostels' which are essentially really tiny hotels based around some funky concept. So, overall, you can expect a comfortable stay. Having said that, there are a few things that I always tell friends when they ask me about hostels:
- A hostel is NOT a hotel: Don't expect bellhops, obsequious hotel-like staff and check-in desks. Most hostel employees are in this because they like travelling and / or want to meet interesting people. Be nice and friendly to staff; practically every time I read a review of a place which claimed 'staff was rude' seemed to me a case of travellers trying to boss around staff.
- You get what you pay for: There's a reason why hostels are cheaper than hotels - they have to cut costs somewhere. So don't expect your bed to be made each day with fresh sheets, free shampoo / soap, et al. It depends on the hostel's management really - some change sheets every time a new guest is allotted a bed, some weekly, or some only when asked; so you may have a situation where you have bed linens slept in by someone else. Don't be turned off by this. Most hostels will replace them on request. Having said all this, there are numerous ways hostels are better than hotels: most of them have free Wi-Fi (something increasingly rare in hotels these days) and free breakfast.
- Rethink your concept of personal space: One of the things that freaks newbie travellers out, perhaps subconsciously, about staying in hostels is a constant violation of their concept of personal space. Everyone has their own comfort zone when it comes to personal space, and takes some getting used to when living in a dorm - what's 'cramped' for you may not be 'cramped' for someone else (although objectively most places ARE cramped). How comfortable do you feel living in a room with 4-10 people, each with their own schedules in the morning or at night-time? How comfortable are you, say, changing in front of others - or seeing others change in front of you? How comfortable are you with how close you like a stranger to be next to you? Remember that most dorms have bunk beds.
- Socialise!: I've put this lower down on the list because many already know or expect this when they want to stay in a hostel. Hostels are fun and lively places, so try to be so. You don't have to go around making friends with everybody if you're the quiet or the shy type, but at least speak to some people and make travel buddies. Don't stay in a shell. Don't go to a hostel and then be mortified of approaching groups or striking up a conversation with someone. If you're an extrovert, you'll find no problem with this. I'm one of the quiet types myself - and what I find is that it's easy for me figure out who the other introverts are hang out with them. Hey, us introverts can be interesting people too!
- Go with the flow: Be less of a slave to your schedule. If you're travelling with a group, great; you probably already have plans. But if you're travelling solo or as a couple, then it helps if you have some leeway in your plans. For instance, if a city takes 'two days to see', then stay there for three days instead. This will allow you some flexibility to hang around other travellers and discover places to see that you might not have had in your itinerary.
- Be mindful of others, especially if coming into a dorm late at night: Don't be a dick. There was this Japanese guy once in Kuala Lumpur in my dorm who got up at 2am and started making balloon animals (true story!). And more often than not there's someone rummaging through his backpacks or plastic bags at night or early morning. If you plan on coming back late or leaving, prep yourself in advance so that the things you need are already out or at least don't need much re-packing. Take care of your traveller karma, even if it's your last day in some place. You don't want to be 'that person' who wakes other people up when they're sleeping and they think "what a dick".
- Use lockers if available: People have different comfort levels leaving their stuff around. Some are paranoid - and if you're one of those types, then make sure you choose a hostel that offers lockers. Otherwise, learn to trust people - but don't necessarily flash your gadgets around!
Having a good hostel experience is mostly about being prepared and by doing so, not getting shocks that spoil your experience. After that, it's all about the people you meet and how you decide to spend your time. Have fun!