You'd think with the "5600" suffix they would have just taken the venerable DW5600 and just added solar and atomic time - but they had to go and mess with it.  In short, the watch has a couple "Huh?" moments that make you wonder what the designers were thinking:

Countdown timer is only an hour, not 24 hours - but the stopwatch goes for 999 hours.  Huh?
Doesn't show time in all modes.  (nice to have in the 5600)
No second time zone.  (to be fair, the new 5600s dropped this too)
Can't set countdown in seconds, but it counts down in 1/10 seconds?  (can't use it for interval training, this irked me the most)
No auto-repeat of timer.  (same as above)

Plus I hear that the batteries in these solar models don't last any longer than if you bought a 5600 and just used regular ole dimestore lithiums - which are like a fifth the cost.  Note that I didn't ding it for this, but go do your own research on how long the batteries really last if you are buying this in order to not have to buy batteries again.  People have had non-solar 5600s running on their original batteries for ten years.

I sent this one back and bought a DW5600E.  If the GW5000 turns out OK I might get one of those.