It depends.
Is it as good as a proper Gaggia (or similar) machine? No, the pressure isn't as high and as said above if you like to grind your own preferred types beans then obviously you can't do that. Also, if you like your coffee really, really hot its not great.
BUT for people who don't want to grind their own, want a small one box solution that doesn't take up too much counterspace, doesn't make a mess then its a great product and way ahead of other capsule devices.
Its one of the few kitchen gadgets I use every day and the range of pods is good, with special editions and the like. Decaff is also good.
Also, the Aerocino milk foamer that comes with some of the smaller ones is pretty impressive.