Gatey it's the same Etrex I use and that's a very good price. I reset the stats at the beginning of a ride and it gives me my speed, moving average, moving time and most importantly for me with time sensitive rides my time stopped and overall average. In terms of proving the distance in an IBA ride they are fantastic. Both OX and I are happy to submit ride lengths based on a photo of the etrex stats at the end of a ride. It allows us to cut the rides to the wire in terms of distance without being concerned that the IBA might disallow a ride for being too short.
TigerBill reckons 2 full days out of the batteries. I use lithiums in mine and I've got 5 full days.
The only down slightly annoying feature with this model is the screen, you have to push the light button to see what it says in the dark. I usually only check it at stops at night anyway. I use it as the speedo in the daylight because it's easier to see than the GPS, Having said that, if I needed another one I'd still get the same one.
Here's the etrex for my recent SS2000K ridden on my CBR125R. If it says 2003kms the IBA won't question the distance.

You can reconfigure the screen to show big numbers and different stuff, here's how OX uses his.

They won't ever replace a GPS. This is the simplest model of the Etrex range. They definitely aren't for everyone.