It's the best Mac I've ever owned.
I skeptically bought a Powermac G4 17 years ago and ended up pretty impressed. Impressed enough to buy a PowerMac G5 a couple of years later. That was quickly followed up by the popular 12" powerbook G4. That combo lasted a while. We added a 21" iMac when they switched to Intel processors and were happy too. The 12" powerbook was replaced by a 2010 Macbook Pro 13" (one for my wife too...).
I remember sitting at my kitchen table waiting for the Apple store to reopen in March 2009 to buy the latest and greatest Nehalem 4,1. There was a lot of hype around the new Mac Pro and I bought it within 10 minutes of it going on sale. I'm still typing on it this second.
Since then, we've added a 27" iMac that I am pretty underwhelmed with. I mean.. it's ok, but we didn't upgrade it very much (they're expensive already) and the 64GB of flash is kinda insulting.
I just haven't been impressed with Apple stuff since they started focusing on the iUniverse and less on the MacUniverse. I'm happy for them that they're making money. I'm disappointed with the lack of innovation. I'm not a Pro. Barely a Pro-sumer. I just like the storage ability of a mac tower.
Last year I built my son a Win10 tower for some gaming. This year, Costco was basically giving away ($499) Win10 14" i5 Asus laptops. I mean... for my consumer use... I may as well use one of those and just break it over my knee, throw it away ever couple of years and replace with the way Mac pricing has evolved.
My 4,1 has been great - and continues to be great. I've flashed, upgraded, replaced, re-upgraded, replaced... repeat.... It's been tremendously flexible. Now, I'm at the point where I'll probably stick a few more dollars into it and just call it "finished" finally after 9 years. I'll probably use it until it dies - I wonder how long that'll take. I don't do any pro work on it. But as my kids have grown, the TB's of video has grown rich along with them.
It's a nice machine, but I don't see Apple inclined to ever improve on that level of flexibility. At least not on the Macrumors horizon.