So easy, just about anyone can make excellent coffee. Most any type of coffee I have thrown at this has brewed very good to excellent coffee... even the worst coffee I have used resulted in at least tolerable coffee.  
V simple to use.  Easy to clean.  Fast.  Very good results, and Repeatable results.
This brews much better "airopresso" than ANY espresso I have every had (sorry Murky... maybe it was just an off day for you guys).

1.  A longer barrel, a stand, or some guides would help (for the inverted method).
   
2.  Slightly deeper filter threads (to use fibre /felt filters) would help
   
3.  A commercial source of 2" food-grade felt filters would help.
   
4.  The markings on barrel and reservoir are pretty subjective and there seems to be only coincidental correlation between them.
   
5.  A case?  Would it be too much to ask for a non-dorky looking case to carry it in?  (sorry, personal trauma involved there).
   
6.  I think that the results do not necessarilly scale as implied (i.e., two two-shot drinks wind up differently than one four-shot.  I haven't tried it with four one-shots).  This effects economy and flavor (but still excellent).

I have owned this for almost three years, and it is the ONLY method I have used since shortly after the first few cups.  I own two of them, one for work, one for home/travel.  I have resorted to taking this to classes with me to replace the free coffee supplied by trainers (Sun's was OK, but Oracle's was un-drinkable).

I HAVE gotten some bad coffee out of it, as any good scientist is liable to do, if he experiments with temperatures and coffee qualities.  Some "Gift" coffee has turned out beyond saving.  The Mermaid's coffee will always do in a pinch, but it's so easy to get fantastic results from just about any bean, that I only do that as a last resort.

I got one just before a family vacation so my wife didn't have to pack both our grinder and our drip machine.  She loves me so much that THAT was our normal traveling behaviour.  The second was won at a rigged company Christmas gift party.

I am responsible for several folks at work finding and buying them.  Others just borrow mine at work, and they all declare that they makes excellent coffee with it.  Even my wife, technophobe that she is, makes excellent coffee with it -- but then, I'm snobbier than she is.  ;-)

I own't bore you with water temperatures and brew times, suffice it to say that if you get one and like it, you'll tinker and experiment until you declare it's the best things since phased plasma rifles in the 40 watt range.  You will want to know what temperature your water is at.

I resorted to stealing one of the kids padded plastic lunch boxes to keep and carry it in at work.  I look dorky, but I have great coffee.  

I do re-use the filters.  I used to keep count until I had hit 20-uses repeatedly.  Now, I just try to remind myself to discard and get a new one if I can't remember how long I've been using the old one.  The felt filter gifted to us lazy experimentors by Rascal has been a unique and wonderful experience.  I lost count on how many uses, and finally had to throw in the towel when it wouldn't come clean and I couldn't tell which side was singed.  If I could cut a straight circle, I'd make a new one with the spare felt he sent, but I've already destroyed two.

I've brewed right-side up, upside-down, and maybe sideways.  The "oils" question was interesting, and I have decided that I can just brew right-side up, although the felt filter really helps that, also.

I keep the pucks to put in our compost.  Sometimes the kids will try to trick their friends into eating the expelled pucks, waiting on a plate on the counter.  They do look delicious.

Easy, but now it would add $10 to the cost, easily.  I drove 30 miles to Sur La Table to get one.  They had just gotten them in, and nobody knew squat about them.  I explained and discussed until the sales person was begging to be let go.  (Not excused, fired).  SLT is a neat store, and they had some other coffee machines set up for samples.  Too bad they didn't have the AP set up, but I imagine that the markup on the other machines is pretty hefty.