After three months of using the Oscar, I have no significant complaints. Any variability in the quality of my espresso shots I can fully attribute to my own lack of skill and not to the machine. And after three months of practice, I rarely get a bad shot out of the Oscar. It is exactly what I was looking for in an espresso machine. Here are some issues, good and bad, that people often mention when talking about the Oscar, along with my thoughts.
NOISE - The pump is noisy, no doubt. If you have one person up at 6AM making espresso while another person in a nearby room is trying to sleep, you may want to consider a quieter machine, or at least some noise-deadening techniques (padding under the feet, put the machine on a solid surface not over/under an empty, resonating cabinet). For us, it's not a problem as we're up during the same hours.
PLASTIC - The casing is plastic (black, in my case). This is a positive for us, as we prefer modern kitchen appliances. While I wouldn't mind a stainless or chrome machine, the modern-looking Oscar doesn't bother me a bit, and it's a cinch to keep clean.
STEAM - We make milk drinks often, and the Oscar provides copious amounts of steam (as most HX machines do, I think). The included 4-hole steam tip will take 6oz of milk from 38 to 140 in ten seconds or so, which was too fast for my frothing skill, so I bought 1-hole and 2-hole replacement tips. So far, the 2-hole tip has worked very well. NOTE: if you get an Oscar and the steam valve appears to be stuck closed, it may actually be stuck OPEN. Try closing it (it takes several full turns to go from fully-open to fully-closed, but during use there's just about a 1/3 turn required to go from no-steam to OMG-STEAM!). The steam knob is unmarked, though there is a little on/off graphic to the left of it. After figuring out where "off" was with the knob, we added a small piece of masking tape to it so we don't over-turn it in either direction (the valve is spring-loaded inside, so you don't turn it off tight like you would a faucet; it's always free-turning even when off).
REFILLING - The water tank is about 1" thick and slides vertically into a compartment at the back of the machine. The Oscar is short enough to fit under our cabinets, but of course then we can't get to the tank. My solution was to cut a couple of small squares of plastic out of a yogurt lid and place them under the rear rubber feet of the Oscar. When it's time to refill, we just lift the front a bit and it slides out easily. The fill spout on the tank is about 1-1/2" in diameter and using a funnel makes things easier. It's not ideal, but also not a huge hassle. You can always just pull the tank out and fill it from the tap, too. We use distilled water with about 2oz of tap water (to add minerals for the low-water sensor) per tank. Note that the low-water sensor, if triggered, will shut the machine down mid-pull. We just got into the habit of refilling it every 3 or 4 drinks.
NO AUTO START-UP - The machine doesn't have the necessary components to allow you to just turn it on and let it warm up. You're supposed to open the steam wand until it produces steam (about 5-10 minutes), then close it and let the machine finish heating up. With a little planning, you can put the Oscar on a timer, but it's definitely not as easy as with a machine that can heat up without intervention. We turn the Oscar on first-thing in the AM, then close the steam valve right before we shower. By the time we're dressed it's ready to go. We could use a timer to turn the machine on 10 minutes before we get up.
NO HOT WATER DISPENSER - It's true, it doesn't have one. We don't drink Americanos and very rarely drink tea. If we did we could steam a pitcher of hot water in about 10 seconds, so it's not really a drawback for us.
For what it's worth, here's our espresso-making process. After three months of practice, we can consistently pull good shots from the Oscar; 25-28 seconds per pull and no sour or bitter tastes. And with the strong steam from the Oscar we can produce excellent, smooth microfoam in just 20 seconds or so.
(The empty double portafilter should be locked into the fully-heated Oscar, so it's hot and stable)
1) Put empty milk pitcher into freezer, fill cappuccino cup with hot tap water and microwave for 30 seconds
2) Purge steam wand to trigger heating element
3) Grind 14.5g espresso (Le'Lit PL53 grinder, .1g digital scale)
4) Pull 2oz water through empty portafilter into shot glasses, and leave water in glasses to keep them warm (this clears over-heated water from HX pipe)
5) Remove portafilter, insert yogurt-cup funnel, add coffee, WDT*, remove funnel, tamp (58mm convex tamper), replace now-loaded portafilter
6) Remove milk pitcher from freezer, add milk and flavoring if any, insert thermometer into milk
7) Pour out shot glasses, start the pull (and usually also a seconds timer/stopwatch)
8) During pull get cup out of microwave, pour out hot water
9) Stop the pull & stopwatch, pour shots into cup
10) Purge steam wand, froth milk to 100 then submerge to 140-143 (our thermometer has about 5 degrees of lag, so we end up near 150)
11) Pour milk into cup creating perfect triple-rosetta (OK not really)
12) CLEAN THE STEAM TIP right away. Other cleaning can wait if you want, but don't let the milk go all concrete on the steam tip. It's a pain to clean.
That entire process takes about 4 minutes, the longest bit being the grind & dose part. The PL53 is a capable grinder, but not especially fast and of course there's no doser so we grind "about the right amount" and then use the digital scale to get the exact dose. We time most of our pulls, just to keep the grinder dialed in. The PL53 is an "infinite adjustment" grinder, and we gain/lose about 1 second per 1/4 turn of the adjustment knob. My next upgrade will maybe be the new weight-dosing grinder from Baratza. :-)
*WDT - in case you haven't found this described at Coffee Geek yet, it stands for Weiss Distribution Technique (after John Weiss of RapidCoffee). It's a fancy name for "stirring the coffee in the portafilter with a needle or paper clip". It breaks up any clumps and distributes the coffee evenly to help ensure the water flows through the entire puck instead of squirting through a channel. We use a small paper clip and testing with a naked portafilter ($90 for the NS brand!) shows consistent results.