Granted, the nespresso capsule system works as promised. The machine extracts consistently good espressos, with thick crema, shot after shot.
I like the looks of the machine, and it's compactness. Heating time is pretty short (2-5 minutes are enough), there isn't much of a thermal mass to talk about. The machine is small and light, same goes for the portafilter, for many reasons this is not the machine you'd want to own if 24x7 operation is what you have in mind. First reason is the capsules price, which should deter most heavy consumers from the Nespresso capsule system altogether, but even if cost is not an issue, better avoid the low end C150, and go to more robust Nespresso models, the C150 does not feel as a machine that would survive months of 24x7 operation.
Another point that I have not taken into account when decided to buy this mahcine and marry with the Nespresso system, was that with my previous machines I regularly pulled double, not single, shots - used double basket with the pervious Gaggia I had, and pressed the 'double espresso' button on the fully automatic Siemens I owned. I did the cost calculations based on single shots... Now of course my monthly penalty, in dollars is twice as high as I thought it would be.
Steaming - this is perhaps the biggest disadvantage of the machine for occational home users that need frothed milk. The C150 steaming system is one of the worst I have encountered. I find myself going for the stove-top plunger most times... this can probably express best what I think about the C150 frothing capabilities. And I have owned two espresso machines in the past, with both of them I was able to froth much better than with the C150.
Robustness - this is not a robust machine... I find it perfectly fine for my needs. Be aware however, that this is a mostly ABS (plastic), light machine. If I lock the protafilter a little too hard, the entire body of the machine flexes when I try to unlock the PF, it does not feel as if it is about to break or crack or anything like that, it just flexes. I'm sure a $1.2K Wega mini-nova, or even the $400 Rancillio Silvia feel much more robust.
Making espressos of Nespresso capsules is quicker and cleaner compared to a manual, ground coffee - portafilter machine, the espressos are close to being as good as the best shots pulled from a high quality home machine (e.g. Oscar). The espressos are much better compared to the ones pulled from a consumer grade fully automatic machine. All that comes for a price - a nespresso shot (single capsule) costs ~50 cents where I live (Israel), this is about twice as expensive as a shot made from good quality beans I can buy by the pound and grind myself or have ground at the coffee shop for me.
If all the fuss around making espressos manually isn't for you, and if you don't mind the expensive capsules, I would recommend this machine. If good frothing ability is important - look for higher end Nespresso machines which might have better steaming system than the C150.
Capsule variety and buying experience - In my humble opinion, they 12 different types of capsules are more than enough to choose from (I have tried 5 different types so far). In Israel you can only mail order the capsules, but that also works pretty good for me. Considering the long shelf life of capsules, maintaining a proper capsule stock at home is actually simpler then ground coffee - I simple place an order every month or two monthes and that's it.