Thimblerigs "weird ability" is actually quite something, if you think about it more carefully!
Even with one piece of this ICE rezzed, you can start swapping it around to bring your other ICE in better positions. A common situation for the corp is that their taxing or positional ICE (DNA Tracker, Data Raven, Inazuma (anyone?!) [...]) is before their ICE, that's purpose is to stop the runner (Data Ward, Kakugo, Tollbooth, Fairchild 3.0, [...]).
Now in order to position your ICE correctly you can only transpose two pieces of ICE if you include Thimblerig, i.e. for two pieces of ICE (independent of Thimblerig) it normally takes you three transpositions and so on. It seems slightly slow, but Thimblerig itself has End the run, which pairs nicely with bringing taxing ICE in position. Also two pieces of Thimblerig accelerate the process quickly (you can do the math).
What else to say? It should be mentioned that Runners who play a decoder, with which breaking a subroutine costs more than 1 (especially you Black Orchestra!) can get pretty mad at this card. Especially if the Corp force a "Reversed-Surfer" style slide letting the Runner encounter Thimblerig again and again.
Give it a shot, it is a great piece ICE and makes glacier style decks much more flexible and thanks to its low influence it is easy to splash!