Welcome to Android! I was like you six months ago coming over to Android after a couple years of iPhone. iPhone is very smooth and generally runs flawlessly. That's because it can only do so much and Apple controls innovation of apps.
But with Android the sky is the limit. There is no way I could ever go back to iPhone now. The level of customization and actual useful apps is just way beyond anything you can do with iPhone. Give it some time. As for lag, I can't speak to other Android phones but the RAZR MAXX HD does have a little. Usually when starting up from a locked screen but only for a second and only initially and not every time. Some have reported longer lag times but it seems to be very subjective.
I will say that if this little bit of perceived lag bothers you then you should try a different Android phone to see if there is one that seems less laggy for you because generally speaking you will not be able do 'fix' it. It doesn't bother me at all. It drives some people crazy. There's a whole long thread on it.
I love everything about this phone. Obviously the big thing here is the battery. Great, long battery life. I stream music 8 hours a day at work and power use for probably 16 hours a day and I still have at least 20% battery left at the end of the night.
I'll agree with what was said above - take your time. Don't go crazy loading up with apps. Load a couple and really check them out. I went crazy and loaded up with apps only to find that there is a whole lot that the stock phone can do already and then I ended up deleting those apps off.
Always check for a free version and try it out first. Sometimes you can get away with just the free version although if I really like a program I'll buy the paid version to support the developers. It always good to read through a couple pages of the most recent user reviews as well as gauging the overall 'score' of the app. Click on the MORE bar in the description and read everything there. I have found sometimes that an app I think will do something will in fact not and saved myself.
Here are the apps that I love with this phone:
Lightflow - great app for controlling your LED notification light. You can make the light flash different colors and speeds/durations/flash rates for different app notifications. It can also be used to give different notfication tones, vibration patterns. Very useful. There is a free version, but well worth the paid one.
Nova - I love Nova. The only downside is you cannot use the stock Circles widget with it which I really liked. But once I got used to the benefits of Nova Launcher I could not go back. I love the cube transitions and the use of gestures to launch favorite programs.
HD Widgets - great additional tool. There are other similar ones like Beautiful Widgets and others. It comes down to personal preferences.
Tapatalk - a must if you are the type of guy that likes to surf internet forums.
Swiss Army Knife - is a great utility program that has a bunch of simple and useful apps.
Player Pro - great music player, I like it much better than the stock player. There are a couple other popular ones. I rarely play the music on my player anyway because I subscribe to Rhapsody so I use that.
AirDroid - great utility that allows you to transfer files to and from you computer over wifi so you don't have to use your cord.
Kii Keyboard - great gesture keyboard. Swype comes stock and works pretty well but Kii is excellent and my favorite. SwiftKey Flow is another one that's pretty good.
That should get you going! Good luck and enjoy the ride!!!