'Generations' was and is one of my all-time favourite stories in comics, but I would agree that it looks dated today, indeed it was a little too old fashioned even in its day, especially considering this was the era of the new wave of youth orientated team books and it's competitors consisted of Wolfman and Perez' Teen Titans, Byrne's Fantastic Four, Levitz & Giffen's Legion of Super-heroes, The New Mutants, etc etc. In its defence though With that standard of competition Infinity Inc had to have its own identity if it was to stand out, and while inherantly old fashioned I feel Roy Thomas did succeed in giving the book its own flavor and most appealing of all its own world in which to stand tall and be major figures. And being in its own world did allow me to forgive its rather staid feel, this was a book looking at the dynasty of heroes stretching back to the War after all.
Being the era of the Justice Society/Justice League annual team-up and with the Crisis some way away the concept of Earth-2 was well established and known. So the attraction of the next generation of heroes who were direct descendents from the likes of Wonder Woman and The Green Lantern was all a great fascination. It had some resonance. Today with so much different and those Earth-2 characters longsince abandoned it can't be any surprise that that resonance and the familiarity of established worlds and characters has rendered Infinity Inc nothing more than an anachronism, it is a book without a context in the presentday, so with little or no chance of intriguing readers new to it. But for those of us who remember the era of Earth-2 and Earth-1 I would say the early days of the series do still hold on to that attraction and the rather impressive sense of a world by which Roy Thomas and Jerry Ordway managed to present on the page...
I agree that 'Generations' was a fun plotline, but I never managed to get into the series, largely because I plain didn't like Roy's concepts for second generation heroes ... the only one I liked was Brainwave Junior.