Been using the Zagg Invisible Shield since iPhone 4, always ben happy with that. I did have a spare Zagg protector I figured I may try to use for the watch - just needed to be cut to size. My X-Acto knife had a hard time making a precise cut.
Anyway, I got the Zagg HD InvisibleShield for the 42mm..hesitant because basically you have one shot to get it right or run the risk of this becoming a air bubbled mess in the process you basically flushed 20 bucks down the toilet. BUT I have the sport and need a little piece of mind to prevent an easy scratch on the Ion glass.
Placed it on last night, pushed out the air bubbles, the curved side is a bit tricky. When I was done it did leave what looked like a real noticeable bubble right smack on the watch face. It didn't look great. I was pretty disgusted, went to bed.
It did clear up though as I slept. I do have a very tiny bubbles - one on the curve below the 7 hour mark and on the side next to the "Contacts / Power" button. Not something that bugged me like last night.
What I didn't like about this is the squeegee they provide. It's oversized, large, and plastic. Made it awkward to remove the bubbles off the small screen. I ended up using one of those small flexible thin plastic "Savings Cards" you put on your Keychain. (Like those keychain CVS BonusCard, local grocery store SavingsCard, etc) That worked far better. It's not perfect, but for now it works.