Charlie Russell was a tad more than "pretty good". Russell was probably the only western artist who portrayed the Indians he drew and painted exactly as they existed in his time and in their culture. Much of the detail in his work is as true-to-life as it would have appeared in a photograph. Most other "western artists" (i.e. Frederic Remington) portrayed Indians and Indian culture the way they thought their work would appeal to buyers who had never seen an Indian. Russell drew and painted what he saw or had seen; not what he thought would sell. (Actually, it was Russell's wife who developed the business and tried to make poor Charlie quit giving it away for drinks in the bars in Great Falls.)
Here's an interesting story about Russell's work that was told to me a long time ago. Some time back in the '50's or '60's after one of the expansions of the Russell Museum; several days before it opened to the public they held a private showing for the elder representatives of the various Indian Nations. Many of the tribes were represented at the event, such as the Blackfoot, Sioux, Cheyenne, Crow, Nez Pierce, the Salish & Kootenai, etc.
The Great Falls collection highlighted Charlie Russell, but had been expanded to feature many other western artists. The person who told this story, Carling Malouf (1916-2007, UM Anthropology Prof) was present, and specifically mentioned the inclusion of some of Remington's work. (One of Malouf's areas of research was Plains Indians.)
Malouf observed throughout the evening that the old men and women would gather in small groups in front of Russell's Indian portrayals and examine them for long periods of time. They would talk quietly among themselves while pointing out the detail of the subject, such as the location, clothes, decoration and paint, the armament, the headdresses or the markings on the horses. He said they would move from drawing to painting and repeat the process. Malouf also noted that when the old ones came across drawings, paintings or bronzes by other artists (such as Remington), they would glance at it and move on in silence, treating it as nothing more than an interesting curio.
Malouf felt that the old Indians were attracted to Russell's work because they recognized themselves and their culture and it was relevant to them and their history. The work by other artists was more abstract or inaccurate and held no meaning for them.
Charlie Russell was a Master and is the most important artist of his time, from the standpoint of historical accuracy. His talent becomes even more exceptional when you consider that much of his work was done from memory. Not bad for a guy who was a permanent fixture at the Mint Bar.