My overall impression of this locomotive (from a 2007 perspective) is "ho hum, another good-not-great brass model". But, I guess if you compare it to other steam models of its era (now twenty-some years gone), it's right in there in the middle someplace.
First off, the looks are great. I mean, it's brass right? So that's to be expected. It's on the performance side where it's lacking (at least as compared to more modern models). The motor is a Sagami "can" (IE, closed), so I can't count the poles. But based on the high starting speed and the really high top-end speed, I think it's safe to assume that it's a 3-poler. The pick-up scheme is pretty much identical to the old 1960s Atlas/Rivarossi steamers. IE, one rail is picked up by the drivers, and the other rail is picked up by the tender (with current conducted from the tender to the locomotive via a stiff wire on the drawbar). The result is somewhat uneven performance overall, with stalls through turnouts and around curves being a common occurance.
Another problem is with the pilot truck. I purposely ran my "J" around a loop containing semi-narrow radius curves (11") and found that the pilot truck tended to hop the rails quite frequently (although, to be fair, this is probably less of an issue on wider radius curves).
The mechanical action of all the moving parts is actually pretty smooth. I didn't note any shimmying, swaying, wobbling or any of the other maladies associated with bad steamers. And overall, the locomotive runs fairly quietly. The running gear does seem to generate a sort of metallic, I dunno, scissory sound, but it's nothing horrible.
Sadly, this locomotive has no lighting whatsoever. It doesn't have any traction tires either, but that's not necessarily a bad thing. I'm assuming that the brass shell provides enough heft for this thing to pull a decent sized train.
So, at the end of the day, this is a less than acceptible locomotive in terms of performance (at least as compared to more modern models). On a typical roundy-round layout (oh, like mine), I found it difficult to complete even a dozen loops without some kind of stall or derailment. Frankly, if I wanted a great looking and great running "J", I'd happily go with Bachmann's 2006 plastic model over this one. Then again, it's brass, so I'm sure it's more than up to the task of looking pretty in a display case.