I would definitely get it!!! I have the 205 which is exactly the same thing as the 305 but without the heart rate monitor. I used to have the 201 (the older model), but the gps sensor on the 205/305 is much more sensitive and will not cut out as much if you are running in trails. I have used the 205 to train for marathons and it is by far the best running accessory I have ever gotten. There are soooooooo many programs that you can use to help you with interval training, maintaining certain speeds, it has a virtual training partner where you program your distance and the speed you want at all times during your run and it will beep at you if you go too slow (or too fast), etc. There are ENDLESS options with these Garmin watches!!! Also, the computer software for these watches is fantastic!!! you just plug the watch into your computer and it downloads extremely detailed information from your workout, as well as mapping routes and keeping track of your progress over time. I discover something new about the watch every time I use it. You will not regret getting it!!!!
Take care,
Ady