It goes without saying you are likely to understand what you are looking at in a lot more depth by having a guide with you. That said, this is also the most convenient way instead of figuring out how to get to Auschwitz from Krakow. Although in my opinion, this is where the advantages of taking a tour to Auschwitz end.
Before I continue, let me just say that I am actually a huge fan of day tours and group activities. As a solo traveller they are the perfect opportunity to meet people and a lot of fun.
Disadvantages of taking a tour of Auschwitz
There are two major disadvantages of a tour to Auschwitz from Krakow, with the first being time. You simply do not have enough time and will find yourselves rushing from one part of the camp to another while never really having time to take everything in. From what I have witnessed, the Birkenau part of the tour is very much a fly-in visit whereby you hurry from one side of the camp to the memorial and then possibly squeeze in a few buildings before heading back to the bus.
The second disadvantage is the most important; you will not have much space to experience this journey on your own. Believe me, I ended up spending a week next to the camps in the town of Oświęcim for the fact that I was so blown away by the experience and can tell you that this is in fact a “journey” rather than a tour. Auschwitz will make you sad, depressed, angry and everything in between but it will also take you to places in your mind in a way that no experience will ever do. It is fascinating, evil, emotional and unforgettable; do you really want a tour guide talking in your ear or to be surrounded by people for four hours while you go through this?
There are educational plaques to explain most parts of the camp and even without a guide, you will still spend time trying to escape some of the groups.
I highly recommend that you go independently for this experience.