Sorry able, but Charlton Heston was great for his time, but pales in comparison to actors of our current generation. I feel like there are literally DOZENS of actors and actresses whose skills far surpass most of the heralded actors of generations past. Not sure if it is just that scripts and the technology of movie making are so much better now, or what, but there aren't many actors (term used for both male and female thespians these days) from yesteryear who impress me.
I thought that The Omega Man, while probably pretty good by 1971 standards, was about as cheesy as it could be. The acting was dismal by most of the actors, and I didn't like the blaxploitation feel of it either. I thought it was probably groundbreaking of Heston to have a black female romantic lead, but it was done poorly. I thought the leader of 'the family' was a better actor than Heston in that movie.
So much less was expected of movies back then, and the movie-going public was a lot easier to convince back then. I'm not saying there weren't quality movies made, but The Omega Man was nowhere near the cream of the crop of it's own year, let alone decade or generation. It wasn't even close to being as good a movie as I Am Legend in any facet of criticism. The plot was better, the character development was better (although I agree with others that Will Smith's character deserved more explanation), the visuals were far more stunning, and the 'believability' was far greater in IAL than in TOM. The 'believability' can be taken as a moot point because most movies, after all, are works of fiction, or at least fantasized a bit for better selling value, but I use the term to mean something a bit more telling. Does the story make sense? Do the characters behave as a real-life person would? Those kinds of questions that can be answered in the affirmative help make a movie better because they help avoid plot holes.
Things that were just pointed out, like the flags flying were in pristine condition (something I hadn't noted before) or that the roads in Vermont looked like they had been maintained, while the roads in NYC were overgrown with vegetation....those are plot holes which suggest laziness or a lack of attention to detail, not poor script writing. Movies of yesteryear were absolutely HORRIBLE at these kinds of things. All that leads back to my feeling that so much more is expected of movies nowadays, and so much more is delivered to the screen in terms of effort and attention to detail.
Will Smith is ten times the actor Charlton Heston ever was, in my opinion. Anyone who can do drama, comedy, action, romantic comedy, etc. and be believable at all of them is a very talented, well-rounded actor. Will Smith is easily that. Charlton Heston is not. Heston was very popular and well thought of for his generation, but again, so much less was expected, it was far easier to be a star and a stud then than it is now. FAR easier.