Can you hear the noise of the vibration and is it loud like a smart phone? Also, what is the battery life like?
How accurate is the vibration? As in if you change it to faster tempo can you still feel like?
Would you recommend this watch over their Soundbrenner metronome app?
I can only speak for the Pulse, but I assume the Core will be rather similar. The Core is more like a smartwatch, the Pulse really is just the metronome. As for the Questions:
1. Yes you can definitly hear it buzz when you are quiet, like a smartphone sums it up nicely (though the vibration is a lot stronger). I wear it on my arm though, if you would wear it beneath your clothes, i.e. on your leg or something I don't think you would notice unless it's dead quiet
2. Very accurate, even with subdivisions or complex rythms. There is a certain point though where the beats get hard to distinguish, as example often times I turn of subdivisions when the song is more then 120bpm because I have troubles "feeling" the single beats.
3. Yes, but I would say beyond 120/150 bpm subdivisions get problematic for me. Really depends what you are aiming for
4. The app works as a metronome, so the core function is the same. It's a great app, arguably the best metronome app out there (especially for free). But the hardware device is something completely different, since you don't hear but feel the beat.
Hope this helps, personally I love this thing. Just some word of advice: The core is (kind of) a smartwatch with a tuner. If you don't play a stringed instrument and need a smartwatch (ie. because you already have proper smartwatch) you don't really need it. When it comes down to the metronome, the Pulse does exactly the same thing.
Most digital watches and fitness watches these days accept apps like my Fitbit. For fun I loaded a metronome app but quickly discarded it. Yes it has beats but you can't look at it to watch the beats and still watch music. My Wittner mechanical metronome does the job for me.
One last remark: This isn't really comparable. The metronome apps I downloaded on my smartwatch all sucked. All they could do was a steady beat and not very precise. No setlist, no subdivision, this was the most basic stuff available. The vibration also isn't very strong on my smartwatch. That might depend on your device, but the vibration on the Soundbrenner is a whole different beast.