Heathkit is actually quite famous for the electronic kits they
produced until the mid 90's I think. For some background, see:
http://www.heathkit-museum.com/I built about 40 kits, and still have nearly all of them. There
is a Heathkit collectors community, especially for the ham radio
side of things.
On to the scope. I actually have this scope too, it was my first
scope that I built as a boy. It probably has value as a Heathkit
collectors item, but as a test instrument I wouldn't pay more
than $10 for it.
Does it work? Well, yes, but it's not a great scope. Mine at
least doesn't always trigger well. It's hard to get the trace
aligned on the screen as you do that with the chassis outside
of the enclosure. When you put it back in the enclosure, the CRT
gets slightly tweaked and the trace is no longer level.
Is it useful? For audio frequencies, sure. For today's digital logic?
Well, maybe not. But the biggest problem is that it's a single trace
scope. Without two traces you can't see the relationship of one
signal to another, and that's a significant loss.
On the other hand, if you really want to learn about how scopes work
and be able to tinker with the internals of one, this can't be beat.
Heathkit made a converter box to turn a single trace scope into
a dual trace -- I have this box somewhere, but can't remember what
it's called. Yeah, that sort of worked.
Keep in mind that you can often find top notch Tektronix scopes
with 100Mhz bandwidth for <$200 on Ebay and they are far far
more capable than this scope.
Scott