As a previous owner of Garmin 205 forerunner, 305 forerunner and 910xt, this feature is an excellent one that I have used regularly in the past when running on my own.
I have noticed with the 735xt however, the few times I have used it, that it shows completely inaccurate time ahead or behind data, most of the time by the end of the run. For example I set the pace at 7:00 minute miling and start my run slower at 7:30 minute miling and the watch correctly displays that I am 30 seconds behind after one mile. I then change data screens and later in the run as I pick up my effort I go back to the Virtual Partner screen. Now for example after four miles in 29 minutes 30 seconds the Virtual Partner screen displays that I am only 15 seconds behind which is obviously wrong as target pace through four miles would be 28 minutes? I then pick up my pace and in no time I am ahead of schedule and it seems to be calculating correct current data, but what about the 90 seconds I lost earlier and I looked forward to catching back up later in the run?
The only time I noticed the data stayed correct was when I did not change the display screen away from the Virtual Partner throughout the whole run. I have a few Connect IQ applications running on other data screens and one of those has no trouble calculating time ahead or behind data which I often set to a different pace so I have a choice depending how good or bad I feel.
Anyone else have similar problems or am I missing something? Other than a few occasional OHR problems and some minor quibbles, I love this watch.