Nothing. We were absolutely contented with the Olympiaworld-Landessportcenter.
We arrived after 11p.m. bec. of the construction works on the Wien-Innsbruck line. I informed the reception in advance about it, as there is no late check in. However, when we arrived (by taxi for 8 euros, as at night the city is almost sleeping) a man was waiting just for us, so we did not need to even telephone. The room was spacious, calm, quiet and clean - originally planned for 3 people, but it was only me and my mother (there was no such an option to indicate on this site). There were extra quilts on the shelves in case of a cold night. A small soap and several towels were at hand to use. The staff was absolutely kind and helpful. The breakfast was very good, early birds are in advance, as the breakfast time is from 7:15 to 9:00, and the first ones have wider choices, however the lady there brought out extra yoghourt. You can eat whatever you want and find on the tables (including bananas and apples). The hotel itself is not in the center, but can be easily approached by the bus "J" and an other one like 4136 (or similar), the bus stop is just some steps away from the main door for both directions.
Advice: buy the Innsbruck card (available at the reception desk as well), but be aware as it is valid from the time of purchase for 24 hours. The Sightseeing tour bus, a red one with a logo, stops at the same bus stop, as line "J" (for both directions). Take a city map at the reception and an other one on the ST bus, the last one will indicate the places to which the bus might take you with pictures on the other side. The card worth the money, as you can enter to so many places withouht paying extra entrance fee, and you can use the buses as well (including this sightseer which has stops at the main tourist points, and you can step down and up wherever you want).