I bought mine (from HF) five or six years ago and it runs through about 15 cycles per week, give or take (I'm a hobbyist watchmaker). It's still doing its job, but the "off" button quit working after about six months... not that I really need it. My other ultrasonic is a GemOro and seems to do its thing with more gusto than the one you're looking at, but for the money the cheap one isn't bad.
The best advice I have is to start collecting small jars for whatever different cleaning solutions you're going to use. That way you can just fill the ultrasonic's tank with water and drop in whatever jar you need at the time. Beats the heck out of trying to pour that nonsense back out of the tank when you're done.
IndyGarage's comment makes me cringe a little bit. A watch's water rating is only valid on the day you buy it and I'd worry about doing this to any watch you can't live without. A toothbrush in the sink would put a lot less pressure on the seals, though that's still not really advisable in the crowd I run with. Unless he happens to have a Rolex Sea-Dweller, in which case, go nuts

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