Incomplete and lots of personal opinion: There are three versions of the Model 1, usually called 1st, 2nd, and 3rd issue. The three have essentially the same design characteristics. The 1st issues cost way more than the 2nd and 3rd and are probably too valuable to shoot. The 2nd issue has an octagon barrel, unfluted cylinder, and square grip. It is the best looking of the 3 issues. The 3rd issue has a round barrel, fluted cylinder, and bird's head grip. Some may think it is the best looking of the three.
All versions suffered from the same faults that developed with use. The hinge at the top front of the frame and the latch at the front bottom of the frame get worn and loose. Either could be frozen by rust. The latch had a spring that may be broken in these oldsters. The cylinder had no axis pin; it was secured at the front by a little round nubbin that fit in a depression in the frame. Wear causes the front of the cylinder to move a bit and wear in the hammer end of the frame can cause poor indexing of the chambers with the barrel.
You want none of these things, of course, in a Model 1 that you would want to shoot and such can be pretty scarce.
Mark Twain had some interesting things to say about this weapon: "If somebody shot me with one of these, and I found out about it, I would be very angry." Or words to that effect.