If the tiptronic is the same as is used in the 3rd gen legacy gt's...I'd say its a waste of money if you HAVE to get the GT package. But if they are smart about it and make it an option on base level legacy's then I would be interested in it.
I drove a '03 GT and was not impressed whatsoever with the shifting. It is the same as an automatic, and downshifting was just horrible. It took 3 seconds to downshift, and the car just lurches forward when you do it. It would definitely be nice for just normal driving, but not a 4000 dollar option.