I built the 6-stall 20+ years ago. From what I remember, if the interior was painted/weathered before assembly to look more realistic (less plastic), and details like benches, tools, and workers added, then lighting should make it look great. On the other hand, if Walthers has changed design or materials, then forget everything I said...
It looks great after I weathered it. It just dose not look like you could see much detail even if you put some lights in it.
Sean, there are many of us who have built versions of this structure. You can see the corner of mine in my avatar, and here is another view I have, many times, contemplated putting some lights in, but it has been low priority