Did you play it shortly after it launched, or some time after? The game was very unstable and buggy for a while after it released, but it's been largely improved since then. There's still a few minor bugs that are kinda hard to fix (usually scripting issues with some quest lines that can be broken, but I think most of those have also been repaired), but otherwise it's very solid now.
Also, are you playing on a current-gen system? PS4/XB1 are going to have really bad performance, even with the updates.
If you didn't quit due to performance problems, why did you decide not to continue? Maybe I could shed some light on things you're missing out on.