First of all, I never really got these future cyborg movies. Of all the shapes we can and have given robots to date, why humanoid? I understand the occasional humanoid, for one purpose or another, but how many functions would be more easily served with robots in different shapes? How many robots out there right now, working in hospitals or under water, or building cars, human-shaped? Not a one.
While we're on the subject of all these movies... that's exactly what this is. Terminator, The Matrix, I'm sure you could name a couple more. This is a perfect example of cut-and-paste movies: take 2 genres that work, in this case, robot invasion and Will Smith, and stick them together. Nothing wrong with that, when it comes to making a good movie, just makes it physically impossible to get a perfect score out of it. Not very original, though there are plenty of ways to go worse.
Despite the lack of originality, I have to say this is pretty entertaining. Maybe that's just me as a Smith fan speaking; there's not much other draw to this movie. There are a few funny moments ("Which one?" "One of us") and a few decent action scenes, but that's about it. It's a one man show, and they just happened to pick the right man to pull it off.
The effects are, of course, modern CGI, though not as bad as some. It's a good use of CGI effects: they're actually imitating something they can realistically imagine, and so it doesn't look like complete crap (even if the robots don't exactly look real either). They're far from awesome, but the robots also aren't the type of effects where you watch the whole movie thinking about how stupid they look (the Green Goblin immediately comes to mind as an example, though there are better ones out there).
Overall, you either like it or you don't. Analyze it, there's nothing in it for you. The originality is lacking, the acting in general isn't very inspirational. If you liked the Men In Black movies, you'll probably like I, Robot too, though don't expect it to be nearly as good.