I have done Freedom bridge, 3rd tunnel, Dorasan station and Dora Tower observatory trip 3 times...unfortunately.
The first time was in 2008 when I had my first ever trip to Korea. I couldn't make it to Panmunjom as I only had time in the weekend and they were closed on Sat and Sun (something they have changed).
The other 2 times I went as part of my Panmunjom trip with friends and family.
I am less impressed to be honest and feel it is mainly propaganda BS (without underestimating the situation with the North).
The 3rd tunnel evidence that it was build by the North:
1) because the North claimed it must have been an old coal mine, but there is no coal to be found in this area ;
2) The tunnel tilts slightly upwards to the south, thus water can drain to the north.
3) The holes in the wall where they stuck TNT point to the North, indicating that it must have been build from the north.
Now, I cannot check on either one of these three. But, since there is a wall build in the tunnel, around where the DMZ should start (i.e. 2 miles away from the north) how do I kno if this tunnel truly stretches all the way to the north? All I know is there is a part of a tunnel that I can see on South Korean soil. There is no footage of the further part of the tunnel.
Then the dynamite holes. How come that the dynamite blows up half of the hole, leaving the other half in tact? Again, I am not an expert, but I do questions such things.
The draining story? I simply don't know.
Then Dorasan station, an expensive way of saying "we wish there was a connection to Pyong Yang". Nothing more to see there. It is as interesting as the architecture of Incheon airport as it was build by the same guy (likely with the leftover materials).
Dora lookout observatory is interesting, if the sky is clear. Otherwise you cannot see North Korea. And the freedom bridge...ah well, guess there is some history.
What is defenitely worth it is going to Panmunjom, if not only for the history of the place. You will see more of the defense by South Korea than anywhere else and you get to go into the UN buildings, crossing the border of the North. With a bit of luck you will see some soldiers on the other side. But don't be fooled, they do the same trip to Panmunjom from North Korea and you get to go into the same building.