WELL,you ask??
My first impression after only an hour and a half is GREAT!!!
This simple antenna held on a 20 foot tall expanding fishing pole and the speaker tripod with the long end tossed up in a tree,tied to a partial bottle of water and feed with 25 feet of RG8X ,called Mini8,coax to my LDG antenna tuner and Yaesu 857D tuned everything I tried.
I could not tune 6 meters BUT did tune 10,12,15,17,20,40,80,and 160 Meters...any not listed I just did not try yet.
I had good reports on 40 meters from a group that included Indiana,Ohio,Texas,and Colorado,
I also got a favorable report on 80 meters from Houston,North Dallas,and Amarillo.
On 20 meters a Ham in New York and one in Pennsylvania replied to my CQ---TEST call with fair reports
as conditions were not so good this foggy morning YET.
The performance was good on 20 and 40 and close to my main ,full size inverted "V" on 80,even though the antenna is a bit short for 80 meters.
No extra counterpoises or ground wires were used...and the wire of the antenna will fit in a sandwich bag with the small 4 to 1 balun...PORTABLE!

More PLAYTIME serious testing is needed and hopefully I can also get input from fellow TSP Hams as the antenna takes so little to build and is easy,even for a man who can only walk with a walker today, to put on the air.
Now,what to do with the rest of this day???
Cool. Essentially its an OCF Doublet for 40M. I'm surprised that it matches well on 12M - 24.9Mhz is one frequency where you're very near a Voltage Loop, with the feedpoint being where it is, 30M and 6M are two others, so not surprising that it doesn't play on 6M.
Have you made any contacts on 12m with it yet? Efficiency is probably not good on 12M due to the impedance being well above 200 ohms at the balun, but when propagation is in favor of it, it doesn't take much power on 10/12/15 meters to make contacts.
Like a G5RV, it's going to be a "compromise" on 80/75 meters. It will work well enough to make NVIS contacts; just know that efficiency will be down around 60%. This shouldn't harm anything, unless you beacon at 100% TX on WSPR running the 'full boat' 100 watts from the radio.
'cause nobody does that just to see how far they can get ;P
On 160M it's essentially being "matched by it's losses". The antenna is 1/8 wl long on 160, and so the impedance looking into the balun [from the antenna side] is probably only a few ohms. The balun is trying to divide this by a factor of four, so the coax looks like it has a short at the antenna end, and your tuner is essentially loading the capacitance of the coax itself. It's the losses in the coax and balun that are absorbing most of the power, and making the antenna look "tunable" from the viewpoint of the tuner. Maybe it's worth a try to see what you can do with the 1~3% radiation efficiency you might get, just don't stay key-down too long or you may ruin the coax, or balun, or both.
Have fun, and keep hackin radio stuff.
Cheers