It was spectacular back in 2000, I owned the Dreamcast version. The scale of the game (maps size, enemies size, etc.), its music (by Jesper Kyd, from what I can recall), the puzzles to solve (mostly with the scientist, Dr. Fluke), the general challenges which were quite above average, if not simply very difficult (especially the bosses, in particular the very first boss), the humor, the sound effects and more... it was just overall a very good game, I always liked it.
I bought it again for the PC on GoG.com, and I started a game again a few months ago, it's still in progress, I play it very occasionally, but when I do I still have the same fun as I had before, even though obviously the graphics have aged after ten years. If however BioWare plans to give the game a boost in graphics quality then I would certainly not refuse it. I wonder if it would work for the current version of the game as a separate upgrade, or if their "HD version" will be considered a re-release and its own game that we'll have to buy to play it that way. I don't think I'll buy it again unless the price is extremely cheap, but even if I don't end up playing it with the high definition touch it doesn't really matter because it's just a great game anyway.
As a side note, to this day I still have to complete the original MDK which I had played for the first time on the PlayStation when I rented it for a few days, I can barely remember anything about it to begin with, I really have to give it another go, it's also available on GoG and I might buy it eventually.
