The Martini Henry is a much-maligned rifle. I did a fair bit of shooting with a Martini back in the good old days, as well as watching far more talented marksmen putting them through their paces; if you point 'em in the right direction, they do the job just fine. The crude-looking standard issue iron sights take a bit of getting used to, but once you've learned how to arrange the foresight in the rear 'V' it's perfectly possible to use them for precision work at 300 yards plus.
Martinis were being made until relatively recently in Afghanistan and northern Pakistan, in preference to more up-to-date designs, because the rifle's reputation was so high among users in that area.
A word of caution for first-time Martini shooter, however; on the back of the receiver, you'll see a small checkered oval. This is where you rest your right thumb. If you wrap your thumb round the back of the receiver, as you would do with any other rifle, the extreme pain you'll experience when the gun goes off will explain why the manufacturer put that checkered oval there in the first place...