I agree with the above comments. Heart rate monitor and calorie counters (sometimes not exactly accurate) may be beneficial to some. Also, water-proof and extra battery life could be an asset depending on training.
In general, advanced GPS functions or wireless connectivity options would be unecessary options for me personally. Also, I do not want to wear a watch that looks like a caculator or cell phone with a strap attached to my wrist...too bulky and complicated, so the simple workout features are fine.
I personally do not use the heart rate monitor anymore, it is good data, but for me, it feels uncomfortable to wear.
I use laps, distance, time, current pace the most. I would like to be able to program advanced workouts, however (currently I carry a piece of paper so I don't forget anything and it is quite unconvenient).
5k: 20:12 (December 31st 2012)
10k : 42:30 (March 9th 2014)
Half Marathon: 1:35:27 (February 3rd 2013)
After completing my 10th HM it's marathon time! The goal is set for March 15th (tentatively at 3h20min, but it sound like science fiction at the moment so I might adjust it down).