In the (language) news
A couple of points to note
- By this time it should be quite clear that using on the other hand on its own is absolutely fine.
- On the other hand, if you start with on the one hand, then you need to complete the pair.
- And if you do start with on the one hand, you can drop the hand in the second part, especially when the two parts are quite close. In fact it probably sounds better like that. (As in my opening example)