We visited the Palace of Knossos in mid September 2007. We got caught out by the devious parking arrangements - so here is a little warning!

As you approach the Palace from Heraklion, you will see official looking parking signs. There are about 4 private parking sites and we instinctively parked in the first, which was on our left as we drove towards the Palace. Luckily we have no trouble walking because it was about a 10 minute walk threading our way between parked vehicles with no real footpath and dodging oncoming, fast-moving traffic. If walking is a problem, do drive right up to the entrance and see if there are any spaces nearer, they appear to be limited, hence the private sites. We were charged 4 Euros, but we did get the use of a lavatory and a free glass of cold water!

The Palace experience is just what you would expect from the most popular attraction on Crete. Hoards of visitors, scruffy surroundings, rather pricy snacks. Personally, I would not take young children, you need a good imagination and lots of patience to get anything out of the visit. There are numerous guides touting for business, we were quoted 10 euros. Those who took a guide seemed to have to stand still for considerable lengths of time. This August the temperature reached over 40 degrees, so bring a hat and avoid visiting at midday!

If you're interested in all of the history of Greece, this is a fascinating site. While some of Evans' decisions are controversial, he did not, by any means, "make it up" as a previous review suggested. He recreated a glimpse into a sophisticated and colorful civilization using his considerable research into the Minoan past. You can see buildings, collections of pots, the famous bull horns, the winding staircase, throne room and living quarters.
Some of the sections are roped off periodically. You might ask at TripAdvisor's forums before you go what sections you'll see from people who have just been there. Do a little research ahead of time unless you join a tour - there are no labels or explanations at the site. Go early, it does get crowded with tour groups as the day goes on. .

I was at Iraklion Air Station in 1961 - 1962, and spent many hours at Knossos. At that time it was "out in the country," and the Air Force ran their bus out to the ruins. I could wander anywhere I wanted, and explore deep into the inner sanctums. There were no shops of any kind near the ruins, and very little traffic.
In April 2005 I returned to Crete and to Knossos. I was quite surpised as to how much the city had expanded right out to the ruins. Many souvenir shops are across from the entrance. The grounds themselves are very carefully controlled with ropes and wooden walkways to keep the hords of tourists from tramping anywhere. The underground areas are pretty much closed.
I would not want to go back again. It is still interesting, but very limited for seeing some of the sections.

I was expecting a lot as this is meant to be one of "the" sights to see in Crete. However I just found it very disappointing.
Most of the sight is sealed off so you can only see things from a distance with little chance to scramble around and certainly no chance to sit on stone thrones.
It also appears that Arthur Evans who discovered the site just made it all up, choosing to move things from where he found them to wherever he fancied.
The whole site is just pure speculation.