Yes, my ds had this.
They did the operation when he was 16 months, on a day surgery basis. The child has to come in on an empty stomach which I thought would be a nightmare, but actually they just get a bit floppy and spaced out.
They put emla (anaesthetic) cream on his hand for about 20 mins before putting in a needle; the stuff was so effective he never noticed the needle going in (I was holding him so that hand dangled down behind me, and he couldn't see what they were doing). The worst bit was when they administer the anaesthetic -- mums are allowed in until the baby is under, which is great for the baby but not so good for the mother, as they look terribly small and vulnerable when out cold. My ds also went a bit blue (not dangerously so, but still) so the last thing I heard as they ushered me out was someone shouting, "Oxygen".
Then you get to pace the corridors for the duration of the operation and the recovery period. At our hospital they kept the parents out until the baby woke up from the anaesthetic -- in ds's case he was so sleepy that they called me in anyway. He opened his eyes, smiled at me, reached out for the bottle of milk I'd prepared, drained all 9 oz of it, smiled again and went back to sleep.
A few hours later we went home. And that was it. You have to keep the nappy very loose for a little while, so need to use disposables if you're a clothie. And they advise you to give calpol/nurofen even if the baby doesn't appear to be in pain, on the basis that it's easier to keep them pain free than it is to get rid of pain once it's built up. So we kept syringing down the medicine for a few days. His testicle looked a bit bruised for a while, but he never seemed to be in any real discomfort.
The op was a complete success, he had two very small incisions, one in the scrotum and one in the abdomen. Both were done in natural skinfolds and are now invisible (he's 6 now). You need to be very upfront with the child about it as he gets older -- they need to learn to check regularly for lumps. Ds is quite happy to correct his mates if they don't call a testicle a testicle!
Do CAT me if you want to ask more.