First thing you see upon arrival is the deck outside the reception, with it's stunning view looking west at the Pacific Ocean. (Great Sunsets, as advertised). Every person on staff is great and welcoming. The owners: Conrad and Emily, bent over backward to help me and my two friends have an unforgettable stay!
We took up 3 out of 4 beds in the dorm. Room was a bit small, but who cares. You should not be wasting your time in your room....what's wrong with you? Provided were large lockers, big enough for my entire 65L backpack, a fan, and AC....which worked wonders and didn't leak like a few other disgruntled posters mentions. It was clean, and we did get clean sheets, pillow cases, and towels when needed.
The restaurant located onsite...part of the deck...was great, and the food was sooo good. You can find cheaper down the road, but not a huge difference really. There was also bbq's open to use, and a kitchen with two refrigerators to store your stuff. While we were there, a group of travelers had a big cookout with kabobs and various other things. Was awesome! There is also a smoothie booth where you can get the freshest, most delicious smoothies you will ever have! Tons of ingredients available to choose from, and they are not expensive...like $3 for multiple fruits.
The bathroom/shower situation - There is a set of bathrooms outside of the main building as well as one inside which multiple rooms share. I personally never ran into any issues. The showers were cold/lukewarm, but granted I always took one when I was hot....so honestly it felt really good. But I understand others are a bit picky.
Activities - Do as many as you have time for and can afford. My group of three did the Manuel Antonio National Park, Horseback Riding, and Quepos Canyoning. All the guides were wonderful, informative, and incredibly helpful and outgoing. I personally highly recommend all three! Others at the hostel we talked to, went on the Catamaran Sightseeing Tour, and the White Water Rafting....Again, they were all highly recommended and worth the cost. (Each company will pick you up and drop you off at the hostel)
On a personal note - It was a friend's birthday while we were on our trip. Emily and Conrad went out of their way, on their personal time to assist with surprising our friend with a birthday cake. How do you beat that? Also, I told them about a wonderful backpacker documentary called, "A Map for Saturday", which Conrad hooked his laptop up to the t.v. and had a hostel viewing party. Insane fun!
Hostel Vista Serena was unforgettable. I made tons of friends! I hope to return to Costa Rica next year, and you can bet that when I visit Manuel Antonio, I'll be staying at Vista Serena. Loved it!