I'm not too sure I would call it fine..tolearable maybe, but not fine.
What's wrong with it? It's four lanes, fairly flat and straight, and not overrun with traffic lights.
The items I mentioned above for improvements primarily.
In sections, it is overrun with stoplights..Evansville, Terre Haute and Lake County particularly. Yes, Evansville is somewhat fixed with I-164, but the other areas are too clogged. Try driving US 41 through Terre Haute during Christmas time. The same can be said for anywhere and anytime through Lake County.
There are also a few unneccessary lights and dangerous crossings all along the route. The speed limit is too low for most of the route, including the nortorious speed trap at Sullivan.
I would like to see the route as an interstate for the length of Indiana. Short of that, with just the improvements I suggested above, I think it would at least be sufficient as both an Evansville-Chicago route and as an alternative to I-65, which is getting too crowded and dangerous, especially between Indianapolis and Nashville.