Uncharted is really great, if you like the singleplayer in the console versions, you'll definately enjoy the handheld version too. There is more than 30 chapters, so a single play through might take around 10 hours.
The melee combat in Golden Abyss is the most fun in the franchise.
It's basically an evolution of QTE's, but when you have to drag your finger downwards,
Nathan ducks after your finger, if you suceed, opponent will miss, if you fail opponent might hit you.
So it feels much more interactive than a regular QTE, since it's making you feel like you'r dragging Nathan around, controlling him, even tough it's just really good animation and design. But it's alot more fun than a button press.
Also you can collect treasures during cutscenes, and similar.
If you see treasures blinking, you can grab it, even in cutscenes..
As for replayability, it's mostly just collecting treasures and similar.
Replayability is beeing increased tough - there's coming a Uncharted strategy card game (similar to Magic - The Gathering) in early december for 5 bucks.
And now all the treasures and stuff you can collect in Golden Abyss will be usable. Since you can buff your card-deck with treasures from Golden Abyss.
That's a pretty cool thing, I think.
I also tought Resistance were fun, it were not as fun as R1 or R3, but it still had the fun weaponry from the franchise, a weapon-wheel, and played OK.
On the downside it were really short, but concidering it's concidered a bad game, you should be able to get it cheap.