This are two reviews in one. The first half is a comparison of TPU vs. silicone material in general. Second half is about this specific case:
TPU vs. Silicone:
Reflecting on all cellphone cases I bought (around a dozen), I have to say that all but one silicon cases disappointed me. I came to the conclusion that the TPU material is superior over silicon for three reasons:
1. Because TPU is far less elastic than silicone, the cellphone doesn't slip out of the case when getting the cell phone out of my pocket.
2. TPU doesn't stretch over time. All, but one of my silicon cases are now bigger than when I bought them. I ran into problems that the silicon started to cover sensors. e.g. the iPhone "thought" that I have it still on my ear after a phone call, because the case covered the distance sensor and therefore keeping the screen turned off. I had to push the phone upwards inside the case so the screen turns on and I could press the hang up button!
3. Silicon is a lint "magnet".
The advantage of a the silicon case is that the grip is much better than TPU. I never(!) had the feeling that the silicone case could slip out of my hand.
Review of TPU SGH-T989 Case:
One of the best cases I ever owned. It has a snug fit. I don't see the phone falling out of the case. The quality seems fine, it doesn't look like it will brake soon.
All buttons have a cut out area, therefore I don't press accidentally a button anymore when pulling it out of (or putting into) my pocket.
I subtract one star for the feel/texture of the case. I would prefer a TPU case that has the grip of a silicone case. Sometimes it feels like the TPU case is close to slip through my fingers and drop to the floor. In the two month that I own this case, I never did dropped it so therefore the feel/texture might be sufficient overall.