Great looks, solid construction, but some major flaws. Makes fantastic espresso. Works well for entertaining/multiple shots. I found it forgiving to learn the art of "lever baristaism". Made me a lever lover and nearly intolerant to pump machine espressi.
Fast heatup times thanks to 1400W boiler.
Large 58 mm group head: good, powerful tamping and a perfect grind are essential for a good espresso. Once this is addressed, the owner will be in caffeinated heaven! But only if she/he can live with the leak problems the machine has...

Poor steam wand: 'Pannarello' style. Has lots of steaming power, but generates stiff bubbly foam. I sealed an air intake hole and got great foam after about 1 month of practice. Apparently, one can exchange the wand with one of the Silvia, which fixes the problem. But I learned to handle mine. Nevertheless, the plastic interior of the pannarello fatigues (see below).  A general replacement pannarello for Gaggias can be bought for $12 - if available (also see below).
Most importantly: it LEAKS, LEAKS, LEAKS. Standard leak on most if not all Achilles: steam wand valve. A construction flaw. Other leaks vary and might be fixed by dis- and reassembly, lubrication and patience. Some leaks come and go while the machine is wearing in. Other potential leaks cannot be fixed by the owner: e.g. leaks at the boiler gaskets that require costly repair returns to a not very impressive WLL/Importika, who are the only Gaggia distributors in the US.
Mid-term problems:
- I started to have problems with the pressurestat after 6 months of use.  The machine had 1.1 bar as set point out of the box, now a standard of 1.5-1.6. Every once in a while, the pressurestat doesn't work and the pressure goes up to max without the boiler turning off.
- the plastic interior of the pannarello steam wand snapped into half due to heat fatigue. Not quite impressive after a few months of one cappuccino/day. The part is luckily also used in the standard pannarello from Gaggia, which is available for $12 (if it is in stock...).
- the group head gasket started leaking after 6 months. It should last 1-2 years with 2 espressi/day. The original replacement gasket turned out to be impossible to get (see below). Again, the general group head gasket might fit since Gaggia used the interior of other 58mm group heads. I ordered one from espressozone (again, see below about Gaggia importer WLL/Importika). I hope it fits...

I love the shots!! Thick crema, rich, silky.  I roast my own blends and/or Sweet Maria's blends. I like the Northern Italian espresso styles, but also am a friend of funky blends or single origins from Sumatra, Malabar etc, as long as they are a bit rich and dark chocolaty. The machine has no issues with oily beans. The group head and other parts are easy to clean and maintain.  
The learning curve is not too bad for a lever machine since the machine can be cooled down with a few pulls. I got great shots within less than 10 attempts. With cooling control and consistent tamping/grinding, learning is easy. And it is addictive...
The boiler has 1300W. 1300W/110V means that the machine pulls 12A! This baby heats up in 5-6 minutes when cold, and it only takes 10-20 secs to regain operation temperature when you pull a shot. It might have one disadvantage: a good electrical system is needed. The lights get dimmer, fans slow down etc when the boiler kicks in. And I have an updated 200A system in the house...

The machine has to be refilled after 1-2 hrs because of the standard steam valve leak and/or other smaller leaks. This means that you will have to depressurize the machine/cool down frequently. The general leak problems are described in many coffee forums, so this is not really an issue with my machine. I assume that's the reason for my machine being a refurbished one in the 1st place...

The design is beautiful, the construction is good, solid brass, stainless steel etc.  While the machine is made from high quality parts, it has assembly flaws - mostly leaks due to poor quality control and a leaky steam valve, which Gaggia never bothered to exchange/update.
Speaking of update: after less than 5 years of its existence, the Achille has disappeared from the Gaggia homepage/production line. The return rate was probably too high to continue the production? This means that it will be very difficult to get standard parts like gaskets, which already seems to be the case. This should be a major warning: seals on almost all lever machines have to be replaced at some point...  I still need to find a group head gasket that would be identical to the original.
It's pretty disappointing that a machine with an original $1300 sticker price is not even supported by Gaggia anymore? Even not after less than 5 years?!  
That's the main reason not to buy it again - it's not produced anymore anyways. I, however, will spend a lot of money and efforts to keep it alive for as long as possible. While all this reads badly, the Achille is my first and very beloved lever machine, and it will cost me probably $1500-2000 to get a comparable HX lever machine.  And it produces fantastic espresso.

While my review sounds quite negative, I really love the machine, I love the HX concept, but I hate the thought of the Achille dying on me sooner than later - maybe b/c a $20 part cracks? A machine of this price category should last for at least a decade - in particular w/o any pumps or fancy electronics. At least Gaggia should support it for a while. It is a shame that Gaggia dropped it completely. I assume it's b/c the market is too small to invest into fixing the flaws? It is a great conceptual machine and it generates divine espresso.

In summary: go for it if you get a good deal and are good at fixing things and finding parts. Plus, if you don't bother about the leaks. The machine will make you a lover of the lever!

Plenty of refurbished (?) Achilles were available from Wholelattelove/Importika. The current price for the few leftovers is $800. It looks as if most are from 2005-7. My refurb was produced in 2005, but I bought it in late 2008 looking brand new. So, these machines didn't sell too much and never were upgraded. WLL/Importika are the only Gaggia distributors in the US, and they are not very good at service and/or parts.  I got mine from WLL via the bay, but it was leaky out of the box and clearly not refurbished. WLL handled my warranty request very badly (my refurb had 6 months warranty- after which some other problems started). They refused to pay return shipping. They instead talked me into installing a replacement by myself - it supposedly was very easy. They then sent me a used steam valve with a broken wand! When I complained, they told me that they won't get any replacement valves within the next few months. I didn't want to wait and/or spend $70-100 on replacement shipping and decided to go with the original valve.  
My attempts to get a new standard pannarello and the group head gasket told me that WLL actually does not seem to have anything in stock. The same for Importika. After placing the online order, I got an email that the parts are not in stock. But I still had to call to cancel. To my surprise, they could not tell me an anticipated arrival time. Apparently, Gaggia parts are sent to them on weekly basis, but they have no option to request a particular part from Italy?! Weeks could pass until a $10 item might or might not be in...