I was wondering if anyone has utilized this for other than transportation and dining requests. Any particular Hyatts completely come through and did others just fail miserably?

I find the e-concierge to be a bit of a waste. For transportation, their options are always so horribly overpriced, you're better off making your own arrangements or hopping into a cab. For other things, the options are limited to what is on their pull down lists for each category and I've just ended up having to email or call the hotel myself because what I want is not on e-Concierge.

I also have mixed feelings about this. I used it twice so far and one time the service was spot on and the other time a complete miss. Requests such as extra pillows and towels were honored both times but one time I requested the roll out bed and it was not waiting in the room when we checked in although it was confirmed through e-Concierge. The other time I requested the dinner reservation and transportation and both were arranged as expected. I will give it a try a few more times before I make my final judgment about this.

I've used the e-Concierge to book spa appointments at resorts where it's best to have an advance reservation. I've also used it to book airport transport at international destinations. I'm not sure I'd use it for anything else, but for these, it's been fine.

I've used it to book restaurant and spa reservations a few times and it worked very well.

I have used it to book transportation to/from airports when I had colleagues traveling with me, and was pleased with the service. Worked well in Seoul, Beijing, and Singapore. In Seoul it did take a little searching for the Hyatt sign that said that all pax with pre-booked limo rides needed to head to the Hertz counter. In Beijing it was terrific as there was a Hyatt rep at the gate to meet us upon deplaning and to escort us all the way through immigration and to the car. I am sure that we could have found our way on our own, but the extra added touch was welcomed.

I would say that if you are traveling with several people the pre-booked transportation is a decent option; traveling alone it is probably overpriced.

Had used it to book restaurant reservations and half-day city tours...

I can only second that. Great service in Beijing ! ^
I also had the comparison in Shanghai and there was 'only' the normal pickup after collecting the luggage.