If you have the old TIE fighters and their spin-offs (interceptor, bomber, fighter, Vader's, etc), then you know how disappointing they are. The blue trim and it-falls-apart-if-you-look-at-it-wrong design come to mind.
This new one absolutely blows those away. Very nicely detailed and very sturdy. The top of the cockpit opens much more smoothly than the old ships. Even the flick-fire missiles work OK on this one (I usually hate those). Great playability. Add in four minifigs, and you've got a good deal.
Now, its not perfect. As good as the detailing is on the outside of the wings/solar panels, the insides of them were overlooked and seem bare in comparison. Some people complain about the new windshield being to bulbous, but that's barely a complaint in my opinion.
Its a decent-sized ship, but the number of pieces is a little low for the price. However, the price is worth paying for the vast improvement in design over the old models and the four minifigs.
I can only hope Lego will build a Vader TIE to these standards!