Further to my last post, I note that Mathematica has released Mathematica Home Edition, for $295. It's the full Mathematica, but for personal use only. And I'm glad to see that the Linux version is included.
The hitch is that it's only available in the US and Canada.
If this offer was available in the UK, I'd be tempted. My other issues with Mathematica still stand, but the high price is no longer so much of a barrier.
Update: The Home Edition offer is now available in the UK, at a price of £195.