Full disclosure, I am an electrical engineer, meaning that the following review will contain references to modifications and tricks that can utilize the full potential of the Gaggia Classic. However, if you're not interested in such and just want to buy a darn espresso machine, I will iterate the advice of many others out there and suggest for you to just buy the Rancilio Silvia.
Now, for all that are interested in getting the most out of your money, or are just wanting a good gateway into the world of home espresso, I would whole heartedly recommend the Gaggia Classic. I have had mine for more than a year now, and it still operates efficiently and, after I mastered all the nuances, can make a pretty good shot of espresso (assuming that a good burr grinder and high quality beans are used).
First, as soon as you open the box find the portafilter and remove the filter basket. You will notice a black nozzle in the middle. This, along with the double and single shot filter baskets, are what make the portafilter a pressurized portafilter, designed to increase the water pressure on the coffee grounds, making the Gaggia a more effective espresso machine. Throw it away. It may help if your grinder is ineffective, but otherwise it just ruins nicely ground coffee beans. Luckily, Gaggia sent along a third filter basket that is supposed to be used with pods, and works brilliantly as just a regular double shot filter basket.
Second, the issue of the pannarello wand should be addressed. I image that the guys at Saeco were really proud of themselves when they decided to take the pannarello wand used with the Saeco Aroma and slap it onto the all of the Gaggia models. However, all it manages to do is create undesirable macro foam, and therefore must be destroyed. The best replacement is the Rancilio Siliva steam wand, which can be bought on WholeLatteLove and easily added to the Gaggia.
Third, because of the rather cheap thermostats, there is a problem with getting the proper brewing temperature. After watching a few videos on temp surfing with the Rancilio Silvia, I applied the same technique with the Classic and found it worked just as well. For detailed instructions on how to do so, just search "temp surfing" or "Rancilio Silvia temp surfing" on youtube and a plethora of videos will pop up. A second temperature issue arises from the lack of a second boiler for steaming, resulting in low steam pressure. This, however, can be easily avoided if, after first pulling your shot of espresso, you flip the steam switch and manage to start steaming before the light comes on. The reason this trick works is because when that light comes on, it means the boiler has reached the right steaming temperature and starts to then cool down. If you manage to start steaming before this happens, the boiler will not reach that peak temperature, and remain on, giving a little kick to the steaming power of the Gaggia.
I hope this review has been helpful. Do not hesitate to email me at firstname.lastname@example.org for any questions about basic espresso techniques with the Gaggia Classic or Gaggia MDF grinder.