No dust jacket, book has never been out-of-print, 1955 edition by Collins... it's not going to net a lot of money in resale, but the content is timeless.

Since your photo (with the dust jacket) says "1120 pages", it would be unabridged, and taken from the anonymous 1846 Chapman-Hall translation. It might be possible that a few words might vary from other editions, but it's basically all the same.

The only OTHER unabridged translation was by Robin Buss in 1996, only on Penguin Books (and exclusive, and still under copyright).

From an reading enjoyment standpoint, the Robin Buss one is definitely superior. But having ANY copy of Monte Cristo is good.