I've been using a Garmin Forerunner 110 with HRM for the last 10 months. I find it great. It wasn't that expensive and really helps to me judge how hard am pushing (or not) in a more objective manner, compared to before where I would just go on how am feeling in terms of tiredness.
Having the Garmin Forerunner means for GPS and HR tracking I can now not worry about taking the phone with me. I think the most disappointing thing about the newly Announced Apple watch is that it needs your iPhone in your pocket to work, which is just a pain sometimes, especially given our wet weather.
I now use this with my iPhone 6 no probs at all.
I love using my phone and Runtastic app, but I really do want a running watch too. Don't know if it's the all or my phone or the area, but the GPS is very poor. Mind you, is brilliant when driving and possibly more accurate that/- 5m
I mainly use my HRM to keep track of the workout intensity, which zone i need to be in for example:
Zone 1 - Improving recovery
Zone 2 - Fat burning
Zone 3 - Aeorbic
Zone 4 - O2max
Zone 5 - Anaerobic