The same situation (on 14.10): It runs with 100% CPU as soon as I connect a backup drive (déjàdup) or a phone (to sync music to the phone, not to index the phone!). Scanning local files may have a benefit, but I don't think scanning any external device without user's intention is acceptable at that cost. Until this issue is fixed, it would better not be part of a stable Ubuntu release.
The same situation (on 14.10): It runs with 100% CPU as soon as I connect a backup drive (déjàdup) or a phone (to sync music to the phone, not to index the phone!). Scanning local files may have a benefit, but I don't think scanning any external device without user's intention is acceptable at that cost. Until this issue is fixed, it would better not be part of a stable Ubuntu release.