I’ve got the Suunto Ti Observer watch – had it for 6 or 7 years – nicely indestructable and quite light. I bought it primarily for Hill Walking/Mountaineering, but to be honest, the altimeter/compass, etc were superceded when I got a GPS – although it’s a nice backup I guess and that’s the reason I still always wear it when I’m walking/biking.
The main weakness that I’ve found is that the altimeter was completely thrown off if the temperature curve wasn’t “normal” as you climbed. It was once 50m out at the top of a 930m hill after I’d set it half way up – basically because it got colder quicker than it “should have”. Had some really mixed results with it overall – some days it was very accurate indeed (albeit with some resets at known spot heights).