Mostly good info here. It's a fair-sized machine, looks like it's in currently-being-used condition, and if that rack behind it all goes with it (don't count on it, unless the shop's closing down entirely) it's a pretty good score for $500.
IF it comes with a fairly good selection of tooling- as in cutters, holders and arbors- it'd make a fairly decent machine. Assuming nothing's broken or badly worn, of course. As a horizontal mill, it can hog off huge amounts of metal, and as a vertical, with the swivelling/rotating head and swivelling bed, you can cut some fun angles and oddball pieces.
On the other hand, the spindle taper is nonstandard. If that toolholder on the table is representative, it's
not a Brown & Sharp taper (or at least the 'standard' ones like B&S #9, etc.) It's probably some proprietary "quickchange" taper of some sort. Again, if the machine comes with a fair to large selection of tooling and holders, this isn't a big issue- just keep in mind you'd likely have to scour auctions and eBay for years to replace or add to.
And, as noted, it doesn't have a quill- in other words, the spindle doesn't move like a drill press. And for day-to-day repair work, at least speaking personally, I use my mill to drill, or just as a precise drill press, often enough that the lack of a quill would be a pretty fair annoyance.
Lastly, you can all but guarantee it's 3-phase. And that means the coolant pump as well. Meaning you'd either need at least a 10hp rotary converter, or a pair of VFD's.
If it were me, and I had the room, I'd take it in a heartbeat. But I'd set it up and use it primarily as a horizontal, and I'd continue to keep my eyes open for a good vertical mill with a quill.
But then again, I'm a machinist.

I like having multiple machines. (Three mills, two lathes, five drill presses...

)
Doc.