Bang for the buck, starter machine if purchased used.
Positive Product Points
Large Boiler, Great steam power, No Burn Case, Easy to clean, Portable, Compact, Well built, Affordable used price, Easy to work on and mod.
Negative Product Points
Not Stainless, No Vacuum valve, Steam knob hard to control unless modded, Factory thermosyphon makes for rising brew temp profile unless modded. Over priced new. NS should add Vacuum breaker and thermosyphon mod to all new Oscars, then it would be worth the price charged new.
I used Oscar as is from the factory for over a year. It was great and I made nice espresso. As there are no gauges, I just had to rely on taste to judge how I was doing. This was a great learning experience, I was not caught up in the numbers just what was in the cup. Oscar is built like a tank. Purging the HX before a pull is not hard, doesn't take long and I used that 3-4 oz of water to warm my cup. Steam power was unbelievable for a home machine and it is easy to clean the case. Large boiler makes it very stable and I never have to wait on the machine. It is a light duty commercial machine and I like my kitchen appliances to be commercial quality. Black case is not flashy and it doesn't draw attention to itself. The case is a pro and a con, it is no burn and very easy to clean but it is not shiny.
Filling the tank is easy, I use the spray hose from my sink to fill it directly and never take it out unless I am taking it somewhere or cleaning it. I don't have to see the water level, I can hear it getting full. I add water every morning and if I make more espresso on the weekends I just add water later in the day. I never run out of water in the tank, (only seen it once when I first started) I just make filling it part of the daily routine.
What I did to Oscar to make it awesome: The mods done were cheap and pretty easy and now my machine is like a Musica in all but looks. I have a steam lever not a knob so stop and start are very clean on the steam and my milk and art are much better for it. I have it on a timer with a vacuum breaker, I have the musica restrictors on it and now the temp is rock solid during the pull. Thermosyphon is where the magic happens. My purge is 2 oz at most, almost not enough to warm the cups. This makes the tank water last longer and the extra slow drippy pulls don't taste burned.
If you can only do 2 things to the Oscar, I would suggest a vacuum breaker and the Musica restrictors. Both are very cheap mods and I think NS should have these on from the factory to keep Oscar worth his new price.
As a starter machine at less than 500$ on the used market, I think he can't be beat. Bang for the buck!