Me loves me my Garmin 610..it was a gift to myself after reaching Marathon Maniacs two stars (silver).
Before that, I had a Garmin 405. Which I also liked..a lot of people have trouble with the touch bezel on this watch..I did not perhaps because I would always lock the watch when I was using it.
The 610 has a cool touch screen which works really well..and it's pretty slim and trim which I want. But I got the 610 because it had two other features I really wanted:
1) It has vibrate alerts. The 405 has a little 'chirp' noise it makes that sounds just like any number of little birdies we have around here 8/ So I'd always miss my 1 mile autosplit displays. You can also set pace or heartrate low/high thresholds and get vibrate alerts.
2) It can display 4 numbers at once. (405 can only do three)
This watch also lets you have 4 different displays and with the touch screen it's actually practical to flip between them on a run (unlike the 405).
NOTE: I set my watch to default to 1 mile autosplits as a default..what most (non-metric) people do.
Here's the screens I use:
1) basic easy run screen. Sorry for out of focus a bit. Shows me my HR and cadence so I run easy but keep up my turnover....but not pace or distance so I don't obsess.
2) Typical garmin 'salt of the earth' display with HR, avg pace and distance.
This used to be what I had on my 405 for most training runs and for marathons.
I used to be very happy just with this display ;)
3) Split timing mode. I use this when Coach Jill has me doing intervals. I can see the current lap time, my HR, my current lap pace and my previous lap pace.
Super useful for hitting the marks spot on during hill sprints or other speed work.
4) My favorite mode: Marathon race mode 8)
Here we have the total time (which is what really matters after all), the distance, the current lap pace and the overall race average pace.
Of course the average pace is something we track and shoot for and I always try to keep that in my expected range (correcting for GPS and not running tangents errors, etc..see below)
But having the current developing mile average is great too! For the first few seconds into a lap, the lap pace is a bit wonky because it only has a few seconds of data..after a minute or two it starts getting more and more accurate. This tells you you need to hit the gas or let up so that you can hit your next mile split spot on...and you can do the correction very very gradually over several minutes.
You'll notice the HR is not displayed. Yes, I do pay a lot of attention to HR during training but during the race it's just a distraction. (I do record it of course)
I used this display format during CIM and it was AWESOME. The only time I missed my splits was when I intentionally let up for a long uphill during that split and then I would gas it a bit on the next mile to bring it back in line.
I also used a pace band for a 3:58 time so that I could track the garmin / tangents losses..which settled in at about 5s per mile (started out for the first 5 miles at 7s /mile). 5s a mile is HUGE: 2.5 minutes in a marathon. Having the total time is a must to use the pace band. (duh)
I'm a fan of getting very close to dead even splits and the 610 with it's 4 number display mode really helps.