VBA is easier to learn than VB.Net. The main difference is that some code words that are in VB.net are not available in VBA. And some VBA code words are used in VBA that you won't see in VB.net. You have to think of it more like a limited, condensed version of VB.net that is made to work for that program. One of the best things to do is to just explore the Object Browser to see the tree of objects available for that program. For Excel, John Walkenbach's book Excel Power Programming with VBA is the one I've found to be the best. Not as much has been written on programming VBA for Word or Powerpoint. You can find some for Access. But for Access you don't need VBA as much as you used to with as easy as they've made it to create macros in Access 2007.
Walkenbach does a good job of explaining how everything in VBA fits together as far as Excel. Some will be very simple for you if you've learned VB.net. But there are numerous portions where he explains why certain things need to be done certain ways. Some examples are:
1. Turning the screen updating temporarily off so the macro runs faster.
2. Deleting rows from the bottom up instead of from top to bottom so you don't skip a row
3. Using the UsedRange and CurrentRegion to limit what you evaluate
4. The differences between the Sheets Collection (Charts and Worksheets) and the Worksheets Collection (just worksheets)
5. Using the Intersect Method to limit down a search and save time
6. Transferring data to arrays and manipulating the data in the array then inserting the data back into the workbook so that just the data is worked with to save time instead of working with tons of object variables, making the macro run much slower
7. Avoiding Selecting and Activating ranges when not necessary
8. Simplifying and modifying the code from the Macro recorder and using it at times
If you have Office 2007, the help search in Visual Basic Editor sucks compared to the old version in 2003. For example if I type in Now() to ask about the Now() time function to return todays time and date it will return info about everythign BUT Now(). Microsoft ROYALLY screwed up their help on VBA for the 2007 Office version. It's like they don't want people to learn VBA. With the 2003 version you had to normally know what you were looking for or get lucky and find it. But with 2007 even if you know what you're looking for, you can't find it in the help section. I find it better to just do a search on the web now. And in the 2003 version they used to provide example code and a list of some of the different values used for some properties. All of that is gone in the 2007 version.