As well as being a tube station (on the Victoria line), Highbury and Islington is served by the Silverlink North London Line, which is an overground overground line, and the WAGN Great Northern Electrics line, which is an underground overground line.
Until recently, the WAGN line had no next train indicators on their platforms, or indeed at any of the stations on the Moorgate to Finsbury Park branch. There's one at H&I now, but there's also a major problem. The indicator board is about 60% of the way towards the back of the platform from the exit. It's also behind a much bigger sign pointing at the southbound Victoria line platform, which is right next door- in fact, you can usually see the tube trains from the overground trains.
This means it's impossible to read the train running information until you get past the static sign, which is further than I tend to walk. Who thought that one up? (Still, Old Street still don't have working indicators at all. I suppose I should be thankful.)