The original was a pretty terrible game. I think the flaws are really blatant though; queue lots of bullet points!
- Customizable weapons, like scavenging gun components from weapons and swapping them around.
- Skill based combat, rather than JUST stats. Most enemies are unfair and cause you having to grind.
- No more bulletin boards handing out missions. Decent NPC's make it more involving.
- Oh and the vending machines, these are just excuses not to design characters as well.
- Give all optional missions a purpose, like working towards a storyline or a foreseeable reward.
- Varied environments, wastelands need to be cut waay short.
- On that matter the devs should read up on level design a little more. Even the few attempts at varied environments were made incredibly dull.
- And work on the cel shading some more, it looked terrible in the original.
- Focus on single player, multiplayer always comes second.
- No defined classes. Make all players start the same stats/abilities and then branch it all out as the levels go up.
- It needs a decent story, almost forgot
I could elaborate on the weapon construction thing, i think it'd work out really well.