tremere110: Not missing anything.
You become president of the USA within minutes of playing SR4. A few minutes later aliens invade. It's just over the top crazy trying to one up the previous game in the series. Nothing in SR3 hints at this happening except the suggestion that the over the top craziness of SR3 might get even crazier in SR4. Nothing.
Vythonaut: So, another day in the office for the gang i guess! I don't know, the 3rd one seemed way too ridiculous in my eyes -- not sure if i'll enjoy the 4th, especially since all those "hero superpowers" sound like you are in some sort of developer/cheat mode; I'll have to see some gameplay action on YT first.
Well, that is more or less the point of the SR series, to explore the ridiculous. But yes, if you didn't enjoy SR3, you probably won't enjoy SR4 either.
Personally I love it. Just last week I played through it for the second time. I like the superpowers, but they do mean that you generally don't use vehicles
at all, except for the few missions that require it. As such, all the vehicle upgrades and customization options are more or less completely redundant. It isn't like using a cheat mode however, since the gameplay is built to accommodate the powers.