If you are in RP games because of 'RP' part - the possibility to create an unique character with any kind of background you like, to play it in the world that is rich in details and based on strong narrative, to embrace unique steam-punk atmosphere and *be* the one that came down in flames, you should buy and play Arcanum.
If you hate so called rpg's where you can do quests only in the way creators thought of, and have no freedom to improvise, you should play Arcanum - because every quest can be done in more ways that you can imagine. Need a ship? Do a quest for dead pirate, or kill the dead pirate, or just buy it, or gamble for it, or steal it or... Get the picture?
If you like strong narrative and unique quests that are written as well as any good book, by all means, get and go play Arcanum.
On the other hand, if you live for next-gen graphics, just do the world a favor and go away from this excellent website :P