My first ST was pre-abs model by choice, and I wrote it off in an incident where ABS would not have helped. In fact, if I had ABS, I probably would have hit the back of the car upright and gone over the top of it into other traffic. I was at fault, which I won't go further into, but having said that I think not having ABS in that situation actually probably saved me from more potential injuries and more serious ones at that. However, situations like that are very rare.
I would recommend to anyone with the choice to go with ABS, as even if it can play up, in the majority of situations of emergency braking, it will save you from hitting the deck. I'd even go as far to say that I doubt anyone could outperform stopping a non-ABS bike againtst one with it. Our reflexes and ability to release and re-apply brakes just don't come close.
As far as reliability goes, it's just like any other electro-mechanical device which can from time to time, throw up errors or fail in some way, but as a safety device, it has and will continue to save riders from going down the road. Choosing not to have ABS because of potential troubles would be akin to choosing a bike with carbies over one with EFI. Generally speaking anyway!
My current ST is ABS model, and any modern bikes I buy in the future will have ABS if they came with it. Not enough reason not to get one with it.