Hi
I've got a 2006 TCR Advanced Team, its a bit more forgiving than the ISP model which is too stiff for lighter riders. Most of my comments can be related to the ISP model as well.
I find it an extremely stiff frame, one of the lightest on the market, extremely short wheelbase which makes the handling what I would call "precise", it tracks from side to side very quickly, compact frame and tight geometry results in a very stiff rear triangle which often causes some wheelspin when out of the saddle, but this can be cured through improved technique. There is a bit of a front wheel overlap which one needs to get used to. The forks are straight and transmit a bit of road vibration and harshess upwards, but this is a small price to play for the improved handling. If your a small to medium sized rider, you'll appreciate the increased standover height, larger riders would find the long drop to the top tube an issue aesthectically. One small point is the difficulty in using large drink bottles with small compact frames, especially on the seat tube bottle holder.
The frame dynamics provides great stability on descents, it has great poise despite the short wheelbase, with no sign of the wobbles that some frames get. The lightness of the frame / package allows you to use a gear lower, so you end up a bit faster on the road. Some reviews have mentioned the lower bottom bracket which can result in pedal scaping when cornering aggressively, I for one have never had this happen, but this would depend on the crank length and frame size and if your doing criterium racing.
There is the usual quality Giant finish, with great attention to detail (fork tips with security tabs, replaceable rear derailleur hanger etc.). Compared to some other carbon frames I've seen there is almost a mimimalist nature to the frame joins, the bottom bracket and chainstay are very slim in comparison to the Cervelo or BMC frames , yet the stiffness is similiar under testing. Also the weave orientation under the clear coat is precisely laid so the frame looks sharp when viewed close up.