Although it's a complete tourist trap, when in Berlin, yes, I recommend visiting the Berliner…read moreFernsehturm. You cannot avoid seeing it from anywhere in Berlin.
There is only one entrance, and you can purchase tickets on site. It cost $34.50 Euros for a standard ticket, which I felt is a little pricey. They search for weapons before you get in the elevator. If you look up while going up in the elevator, you get an interesting view of the interior.
Once you get out of the elevator, you are allowed to roam all around and get a view of all of Berlin. There is also a bar, where I purchased a Latte Macchiato and Salzige Brezel. Even though my drink was machine made, it wasn't bad. The salted pretzel, however, was the driest pretzel I've ever eaten. The bartender was friendly, but a little slow. Seating is very limited. Only a handful of stools.
After heading down in the elevator, I perused the gift shop. Didn't purchase anything though.