I've been training for a half marathon for awhile and used HalfMarathonTrainer quite a few times. Probably the best feature to me is that it is a program already built in that is very easy to follow along.
Bad part? Here in the winter I've been running indoors on a track and it couldn't be any worse as far as accuracy on distance and times sadly. I run with a fitbit as well so I know how many miles I've actually ran, also can tell obviously by how many laps I've ran, but it would be great to be able to count on just one app for all of my running needs. When I say inaccurate I mean, I actually ran 5 miles but it's saying I've run 3 in HalfMarathonTrainer , maybe it is just a poor connection and it cannot register the GPS signal? But I've tried multiple indoor tracks and all have had the same problem.
Now, that said, when the spring comes around and I'm running outside, I'm sure it will be better.