The Barista Express Impress (BEI) is like a Ferrari - and the first couple of coffee (g)rounds will be miserable until you know how to handle the performance!Fill up the machine with water and coffee and start optimizing your espresso experience. Since the pump in the machine is set to a fixed flow rate, you need to tune the pressure for the coffee (and its taste) with the granularity of the coffee: this is done with the default insert - no need to add a filter to a "cup" (filter) to the PortaFilter (coffee scoop).Read and understand the manual. It explains in detail how to adjust the grind size and the (auto) dosing of the coffee.If the coffee flow starts almost immediately with pressing the 2-cup button and there's virtually no pressure built-up while brewing, the coffeee will taste sour (acidic), show some foam, and give you the impression that it is "strong" (with plenty of volume). This is the worst coffee the BEI is going to produce by default - throw it away. Now decrease the grind size (lower number) by about 4 units.If the coffee flow starts after some 15 seconds with pressing the 2-cup button and the pressure builts up into the "Espresso" range without any significant coffee flow (very low volume), your coffee will be bitter and overwhelming. This coffee can be diluted with the built-in hot water dispenser (great for tea with its 90C, too) but it's a rather specific taste. Better increase the grind size (number) by about 2 units. Try again!The optimal coffee should taste neither sour nor acidic, but instead have a somewhat "nutty" flavor that leaves a pleasent aftertaste - even without dilution or added milk. If you need to make changes now, adjust the grind size by 1 unit until it matches your preferences either way. The auto-dosing will adjust to your grind settings within a couple of coffees.TL:DR Go by taste and volume - not by pressure, flow rate, or weather. Make sure to use filtered (fridge) water and fresh beans. Otherwise: crap in - crap out!There's a couple of things with the BEI that made me smile and are a very nice touch: 1.) There's a hidden tray behind the drip tray (under the water container) that provides enough space for all additional tools and "cups" (filters) that come with the machine. Very thoughtful! 2.) There is a "Razor" trimming tool (see photo) that can be useful to trim away excess coffee ground volume when playing with the grind sizes. It's not critical, but its a nice touch and a pleasent piece of metal to play around with while making a coffee. 3.) The water container can be left in place, so you can move the machine closer to a way and simply fill up the container from the side - the container cover elegantly folds to the back. 4.) I mentioned the hot water dispenser above: it's useful to dilute your coffee without messing up the grind size and you can make tea if you don't feel like caffeine today. The temperature is perfect and the flow rate is fast!There's one thing that bothered me when installing the BEI and it could've been covered in the manual: When setting up the machine, the pump was priming the system, but there was no water flowing (shower screen, hot water dispenser, or steam funnel) for something like 5-10 cycles and I thought the machine was broken (making some very concerning "dry pumping" sounds).Another thing that could easily be tracked by the machine is the flow time. There's a already a very nice bar indicator for the compression of the coffee ground, so just add an indicator for the flow time sweetspot of around 30s with bars adding 2 seconds in each direction. Would be a nice touch!All in all, the machine is fantastic and produces amazing coffee - if you are bringing some patience to learn its tricks. Looking forward to my next coffees!