This is (I believe) the full list of known issues posted by the Nike Rep over in the Nike forum. All were introduced as of iOS4.
http://forums.nike.com/thread.jspa?threadID=31896&start=50&tstart=0
User cannot view summaries of individual workouts recorded before new OS installation.
User cannot link sensor, or can only link sensor after many difficulties and/or resets.
Pressing Home button during workout did not create spoken feedback. (Note: one user mentioned that the problem only exists for him when the screen is locked. Other users did not note whether screen was locked.)
User cannot successfully resume paused workout. Chronometer is active, but pace and distance are not detected after pause.
User cannot see Nike + iPod tab in iTunes until after first upload with new OS.
After pausing workout, playlist returns to beginning. (Note: some users specified that they were shuffling the playlist when this occurred.)
When kilometers are selected, screen continues to display miles.
Calibration status does not reflect existing calibration until after first upload with new OS.
Spoken feedback occurs only at halfway point and for final 400m countdown. (Note: one user mentioned that this issue occurred only when he ran a custom-distance workout. Other users did not note workout type.)
Spoken feedback volume is uncomfortably high and cannot be adjusted.
Date of first workout recorded with new OS was incorrect on the device (11/30/02), although it uploaded with the correct date.
Workout distance totals are double the user’s true total distance.
During workout, distance and pace briefly display “0.00” when screen is first unlocked.
User cannot link Watch Remote, or can only link Watch Remote after many difficulties and/or resets.
Spoken feedback is inconsistent (unspecified).
No data point on graph is created when user requests and hears spoken feedback.
User can no longer fast-forward by pressing Home and swiping the screen.
Spoken feedback occurs during first half of workout, but not second half.
5k distance workout exceeding 5k cannot be calibrated upward.
No data point on graph is created at mile or kilometer marks.
Playlist is out of order and repeats tracks.
Deleted workouts are not removed from history.
Device does not auto-pause when user is idle.
User can activate the sensor successfully only in time-based workout mode.
Distance of new workout is not added to workout totals.
Halfway point spoken feedback occurs twice.
Minutes are counted as seconds in workouts under 10 minutes.