This "colorful" pension has quite a bit going for it...friendly staff, kooky decorations, great location and reasonable rates. The rooms are comfortable and well equipped, if not spotlessly clean, and being that it is a stone's throw from the Mariahilferstrasse (main shopping street) and the Museumsquarter, it's price cannot be beat.
This said, Pension Mozart is probably best suited to adventurous bargain travelers under the age of 40...a spirit of adaptability is necessary as this does NOT feel like a hotel, or even a B&B, but more like y ou are crashing at your eccentric grandparent's house for the weekend...the house has a quite strong smell to it as well.
All in all, a mixed bag.

Location is the best thing about this hotel - remember it has only one star! Five munites walk from all famous places in Vienna, plenty of places to eat around.

Rooms are reasonably spacious ( we had a regular double), furniture is 50 years old, TV at least 15 years old, TV remote fixed with a Scotch film, bed is so-so, pillows are awful. Clean enough, bed made every day, towels changed every day. Noisy, especialy if your window is overlooking the street (garbage collection cars start at 7-00 European time! with horrible clink-clank noise. Earplugs solve everything).
Breakfast reasonable - you do not need a variety of 10 meats and 10 cheeses in a 1-star hotel. Three kinds of meat and sausage, two kinds of cheese, sevection of packaged joghurt, two kinds of bread (rolls and rye bread), fried eggs, hot beans and sausages - on a self-service table. Maid brings a sweet home-made crepe with whipped cream, chocolate and nut to each client. Coffee from a coffee-machine, drinkable.
Staff extremely helpful and polite.

Important! Hotel is on the second floor of a regular building BUT - elevator is on renovation till June 2011. Note if you have heavy luggage. We asked the reception man to help us.

This hotel is in a great location - walking distance from Museum's Quartier, in the Mariahilferstrasse shopping district, pubs and restaurants are close by.

The hotel itself is in a pretty run down building with a dark lobby entrance. My room, which was the budget double, was unbearably cold even with the radiator all the way up. The owners provided extra blankets to help and I rearranged the curtains in the room to try to ensure as much heat as possible from the radiator reached the room instead of the window well. Still, leaving the covers was nearly unbearable and, while the proprietors said they worked to improve the temperature, I think the slight warm up in the room could only be attributed to a warm up outside.

I am recommending with reservations simply because the location was great. I would say try other places nearby and, if you can't find one in your budget, go with this place.

I stayed here several months ago and I still remember that check in at this hotel was till 19 p.m. Our flight has been delayed and I sent e-mail asking to wait for us if it possible. I was promised that they would wait for us. In fact our plane has landed in time, even a bit earlier. So we arrived at the pension appr. at 18 p.m. And the first thing I've known upon arrival that room I booked is not available. It was pretty weird considering the fact I contacted the hotel in advance. Moreover I was suggested to have an available triple room - and pay exactly for triple room, although I booked the cheapest twin room with shared facilities. It is not fair and it's not OK at all.
I understand mistakes happen, but all around the world it goes without saying that customer can't be responsible for the hotel's mistakes.
Finally the owner made a discount for a few euros but I don't think that hotel is an appropriate place for arguing about price.
As for the pension itself, the best thing is location which is extremely convenient. As for the room, I didn't like a few things - very old cheap furniture, strange smell and the curtain instead of the door to the bathroom.
Next time I'll definitely try another place.