The North Wall is a popular alpine ice climb, offering 250 meters of either bare ice or snow depending on conditions. The center of the face has some exposed, rather dirty-looking rock. It seems that people usually climb to the right of these rocks. Escape is possible to the ridgecrest on the right after a couple of pitches.
The ease of access, the fact that it's a high mountain, and the glorious ski descent down the valley in winter/spring all combine to make this a premiere climb of the Ötztaler Alps.
Follow any north-side route to the mountain. I'll mention two ways:
1) From the Pitztal ski area.
Take the lift up to the Mittelberg Joch (3166 meters) and descend easily onto the Taschach Glacier (shown as "Taschachferner" on some maps). Head due south on the left side of the glacier on the best line through crevasses, then go west (right) beneath the steep wall of snow/ice/rock.
2) From Mittelberg via the Taschachtal (Taschach Valley)
Walk or ski up the gentle road towards the Taschach Haus (overnight possible here). From the Haus, follow a trail south and east to reach the glacier. Climb the glacier either to the Mittelberg Joch, or pick a line across the glacier to maybe get to the base of the wall quicker (or maybe loose time in crevasse fields, I'm not sure).
Climbing the face.
Once at the base of the wall, the best ascent routes are generally right of the rocks in the center of the face. On my ascent (April, 2007), we could have had bare ice with rocks sticking out on the left, bare ice in the center, and snow flirting with bare ice on the right.
The route is about 4 60 meter pitches in length when roped. A rack of 8 ice screws should be sufficient.
Note: I haven't seen the route in summer, but I'm told that accessing it can be difficult due to melt-out at the bergschrund. In spring, we stepped easily over it.
If the route is bare ice, most parties will want rope, ice screws, tools and crampons. If the route is snow, some parties will be comfortable soloing with a good ice axe self belay. In either case, always bring two tools and crampons.
The route is often in great shape throughout the winter, in which case skis are advised. Getting down the valley is not a difficult proposition, so intermediate or beginning skiers should be okay. But they should at least be skilled mountaineers experienced with crevasse dangers.
BasisLager seems to have an endless stream of reports on this route throughout the winter and spring. Use this site to get up to date conditions.