I have read Frankenstein before, but that a long time ago, and I have certainly never read the 1818 version of the book (which was the first published; Shelley rewrote and added to the book twice, and the version which is most often read was the last version, published sometime in the 1830s). 

Its been way too long since I read that final version to say for sure that I prefer this version, the first one that she wrote and published. I can't say for sure that I feel like the other version has been bloated a little by additions. But this one is streamlined and very clean, and was an excellent one-day read which I enjoyed very much.