I bought this game in 2000, still have my huge ass original box and CD.
I had a hard time getting into it at first, it freaked me out for one thing, and the interface was somewhat cumbersome compared to things I'd played before. I was not much of an RPG type and I hadn't played a lot of stuff with such a detailed inventory, etc.
If you just got this game on GoG, PLEASE stick with it. It's fantastic. Load it up with what mods you can to make it look better for you if you must... but please see it through to the end. Likewise with Thief 1 and 2, please play them.
These games are absolutely phenomenal if you can get past their age and such.
Deus Ex 1 likewise. I feel so lucky that I played Thief 1 and 2, Deus Ex, and System Shock 2 while they were still new or only a couple of years old. I know it's hard to stomach games of that age now for a lot of people, but I bereeve in you Kyle, you can do it.