Learning curve is fine, but the program is simply not stable enough to handle a very large library. If I could get it to work even once, I could back up the library. And if it has this many issues with smaller photos, no way I want to try with my RAW libraries.
It's simply a consumer product, and not designed for serious use with large amounts of data. Not sure what us then, hmmmm. Putting that much data in one library is probably too much for any program.
I think that I will create smaller libraries by year and see if it can handle smaller chunks of data.
It is most certainly not a consumer product.
But let's get to the topic at hand. Yes, it's a bear to import huge chunks of data all at once.
So, don't.
Take a substantial but not staggering amount of photos, and import them.
Then quit Aperture.
Then re-launch it, and import some more.
I suspect you're running into the same problem I did - Aperture grabs a lot of RAM during import, and if you're importing huge swathes of photos, you'll wind up in trouble. Quitting Aperture will free up the RAM, and you'll be able to import more photos.
Again - I have a near 1M photo library in Aperture - so it can be done.