It's very goo.
Is it worth the coin? I'm not convinced.
Couple of things I noticed getting one.
It is not a muzzleloader/non-firearm as per ATF, the box comes with instructions to the dealer to process as a rifle and fill in a 4473. If that matters, that matters, but it probably doesnt matter.
The stock trigger is of course, as per all Remington 700's, horrible.
All reports from serious users have shown that using it with BH209 seriously degrades the breech plug.
The breech plug is a royal PITA to remove.
It DOES shoot decent groups right out of the box with the load recommended here: https://www.randywakeman.com/Remington700UltimateMuzzleloaderLoads.htm
Yes it is capable of 300yd shots.
Gun is somewhere in the region of $800 I think, plus you'll need the scope base or rings, which are regular Rem 700.
Extra costs are those custom case things for primers, but honestly you'd be better off buying a complete replacement breech plug system from Arrowhead Rifles.
After getting a 700 ML for a friend, I decided to go a slightly different direction after shooting his, which did cost more but I feel was a more worthwhile investment.
I bought a Thompson Center Encore pro hunter frame, and then an Arrowhead Rifles barrel in 45. This uses bullets you swage using the supplied tool to create a custom, non-sabot based round that fits perfectly. It fires a 300gr bullet with exceptional BC and using either blackhorn or H4198 I am getting faster speeds than I was from the Ultimate loads.
The cost was more, pretty much double, however with the Thompson Center I am not limited to one caliber. I can buy all kinds of different caliber barrels, centerfire rifle, pistol, muzzleloader etc.
The spring kit to reduce trigger to 2lb and improve every spring in the gun was $25.
This is the video that got me interested in the Arrowhead Rifles in the first place
https://youtu.be/pArj2QOMQ90
500 Yards with a Muzzleloader - TC Encore Muzzle Loader How To's