I have this machine.  It has worked well for me, both in cabinet making (I use it to final sand panel doors) as well as lutherie.  About five years ago I paid $850 for mine new, plus a Delta mobile base. 

You need a really good dust collection system for a machine like this (regardless of manufacturer).  I use a 2HP 1200 CFM Jet dust collector, which does a fine job.

For $550, I'd go for it, assuming it is in as good shape as the photo suggests.  The sandpaper alone is worth about $50.  I don't have the pneumatic drum (nor do I want one).  Unless you have a large shop, invest in a mobile base...Delta's.

Most of all, READ AND FOLLOW THE SETUP DIRECTIONS WHEN YOU GET THE MACHINE HOME!!!  Start over as if it was out of the box!  You'll learn a lot about the machine in the process and will be able to make better use of it.   TIME SPENT UP FRONT WILL SAVE YOU MANY HOURS OF AGONY LATER.  Plan to spend at least 4 hours getting the thing set up right, plus another two hours once you've figured out how it should ultimately be adjusted.

Also, do not confuse this machine with a planer.  It will remove only about 1/128 inch of material on each pass, maximum.  Even that amount is pushing it big time for hard woods.  Patience is a must.  Practice on scrap.  Save the BRW for later.

Invest in plenty of sandpaper.  I rarely go coarser than 120 grit or finer than 220.  Buy one of those rubber disk cleaner sticks...it makes the paper last much longer. 

Run the feed speed faster rather than slower until you get a hang of the machine.  If the wood feels warm coming out of the sander, increase the feed rate.  If the drum stalls reduce the depth of cut. 

Once you've reached final thickness, run the material through slow without changing the depth of cut.

If sanding ebony, go real slow (shallow "cuts") and be prepared to replace the paper.

Pay attention to the feed belt tracking. 

These are great machines...if set up and used properly.

Lofton