Had the Benelli factory one fitted from new. Says Gemel on the key fob, but from memory it's a Meta alarm I think.
It's a bit sensative to washing (ie it goes off if I sponge clean the clocks) but has never played up in the rain.
It also has some strange "power save" sleep modes (requiring ignition to be turned on before alarm can be turned off if left to stand for > a week).
The flashing LED is in a daft place on the RHS of the clock surround behind the right clip on, but this might just be a silly instalation (was done before I picked the bike up)
I keep the bike on an optimate trickle charger in the garage, so haven't had any issues with it draining the battery.
Apart from that, no problems (and it doesn't have an anoying blip noise every 30 seconds some some other makes

)