I'm buying an iPad mini is 16GB enough?

Hard to say. The only real storage hog in that list is the music. Depending on how much you want to carry with you, 16GB may be fine, especially if you use a cloud service like DropBox for other file storage and access.

My first iPad (original, WiFi ony) was as 16gb model and I managed pretty well with it, but still chose to go to 32GB when I purchased the third gen this year. I should add that I have a sizable music collection and use iTunes match, so have ready access to my collection when I'm connected.

On the other hand, you cannot upgrade the hardware on an iOS device, so if there is any doubt, you might want to save a littel longer and go with a 32GB.

This is a personal decision but I suggest buying the largest storage you can afford. I would definitely consider 32 GB though. If you eventually download movies you will need the extra storage.

You can regularly sync the iPad to your computer and keep a lot of the lessor used files there until you really need to have them on the iPad. That will save space for sure.

If you aren't planning on downloading many vidoes and movies, 16Gb should be just about enough. You may still feel a little cramped further down the road, but it should suffice for the forseeable future.

If you plan on dowloading movies, then 16GB will get used up impressively quickly.

Its your call wether you want to wait and save some more for more space. You can of course manage your space, by cleanign up and deleting unised things regularly, so the 16Gb last a bit longer.

I have a 32GB iPad 2 and it is more than enough. It depends on how many movies, apps, games, etc. you want to use. An average movie is about 1.5GB in SD.