Borderlands 1 is definitely one of my favorite games, and I first played the game on my own. Once I started playing with friends though, I had much more fun. Nowadays games are forsaking split screen in favor of online play, and I think you have to look no further than borderlands to showcase just how awesome split-screen is and why it should be in every game. I just did another playthrough of borderlands 1 with a friend of mine on my xbox one (backwards compatibility) and it was just as fun as when I played it before. Being right next to someone as you play with them just can't be compared to online play.
Yes! I sorely miss the experience of playing split-screen with a bud. I don't really have anybody nearby who's willing to play it split-screen with me, so I've had to settle with online play. But I wish games would go back to the split-screen play with online play as well. I generally set up a Skype webcam call whenever I can't play split-screen in person.
Split-screen is so fun, I went through Halo games so fast simply because it was entertaining to go through one with a friend. You also don't get stuck as much.