One more thing (trivial enough to post to Sandbox). Besides adding a new afterword, the reissue omits a section from 1985 called "Life for Home Computers." While I'm sure this is obsolete, and omitted for that reason, my curiosity is piqued. Anyone know what's in it? I must have read it at the time, but I don't have that copy now. The rest of the book has stood the test of time for the most part, granted some of Conway's computational constructions can be simplified (e.g. the "problem" of sending a glider 90 degrees without inverting; Buckaroo was known by 1985, right?).
Poundstone also made some comments about video displays that seem silly in retrospect and he acknowledges it now. Indeed a display that showed a large (Gemini-scale) pattern at one pixel per cell would be infeasibly large. It is a funny blindspot to ignore the possibility of subpixel resolution, but understandable at the time, when the vast majority of people fiddling around with Life really did associate the universe with the display (but Hashlife was also known by then, so clearly not everyone did).