Depends on what photography you do and what lenses you have. I see no justification for upgrading my original 5D yet for general use and landscape. For the things it doesn't do well I bought a 1D (was getting a 7D but got carried away) but find even the 1.3 crop factor limiting in general use. One thing to watch though is software support, especially if you have or get a newer canon, as 5D compatibility with upgrades is not 100%. You are OK if you stick with only that available from the 5D page at canon.co.uk but watch out for o/s upgrades. I bought an imac at Christmas and it is not binary compatible with my 5D disks - this would affect all early canon software.