Brandon Routh manages to read uncannily like Christopher Reeve (the glasses and hairstyle help a lot), and Kevin Spacey also manages to look a lot like Lex Luthor as played by Gene Hackman, which helps the illusion of continuity. Characterizations are somewhat different, however. Superman in this film is a bit more conscious of his alien-ness, and both Superman and his Clark identity are somewhat withdrawn--as might be expected of someone who had just spent five years alone in space. Luthor is a cheerfully megalomaniacal sociopath--almost "Joker"-like in some ways (Lois: "But millions will die!" Luthor: "Billions! Once again the press underestimates me!") but also ruthless. When he does have Superman at his mercy, his attempt a murder is swift, direct, and brutal. No "Batman" style deathtrap here. One may wonder why a man supposedly as brilliant as Luthor surrounds himself which such dull followers: his gang are thugs ordinaire, and his mistress (played by Parker Posey) is a shrill shallow floozy right out of Damon Runyon.
Kate Bosworth is a believable and generally competent Lois Lane--she rescues Superman handily in one scene--and mostly avoids the annoying "heroine" tendency to waltz carelessly into peril, although she foolishly unbuckles her seatbelt during an aerial crisis and later takes her young son with her into potential hazard that becomes very real.
The film is generally quite well done and very enjoyable, with a few surprises, behind the cut:
One major, and rather nice, surprise is that Richard White, Superman's rival for Lois' affections, does not prove to be a villain or a poltroon. Richard is a good, competent, and brave character, in his own way quite as heroic as Superman. The Superman/Lois/Richard triangle is NOT resolved by the end of the movie, although Superman is definitely back in Lois' life in one capacity or another.
The other significant development is that Jason, Lois's son (Tristan Lake Leabu)is evidently Superman's child. Certainly eyebrow-raising to say that the highly moral Superman got it on with Lois at least once before departing for space, out of wedlock, and I'm surprised I haven't heard more howls from either purist critics or moralists already alerted because of the Superman/gay fan connection already bruited about in the press.
Overall, very well done. I'm not sure I really care for the subdued red in the new costume, and the low-relief 3-D chest symbol does make me wonder where he got it from. (Canonically, Superman's orginal suit of tights was hand-knit by Ma Kent with yarn unravelled from the Kryptonian blankets that accompanied baby Kal-El to Earth--).
I thought it very well done on the producers' part to use the orginal John Williams theme, and also to prominently include a nice dedication to Christopher and Dana Reeve.
Reccommended for fans of Superman. No foul language, no nudity or sex, but intense violence and danger scenes are too strong for young children.