Sure, I would jump through. My life is lacking adventure and this would hopefully be just the thing to cure that.

but they might be pandas!

I would not step through the rift because I would miss my life and friends on this side of the rift. What if there aren't any videogames on the other side?

yes ofc because this is higher than one person existence and i just have to know whats on the other side

Since you did not specify any rules I'm going to assume that the rule is to not answer the question.

I'd go thru. Why not, life is a journey and it ca be a great experience

I'd take a gun,a hunting knife and some canned beans, and jump right through. I don't know why, I just would.

Yes,I will jump because this world (or,at least,Italy)sucks and any other thing must be better then this,even a dimension full of evil aliens XD

No, not likely, kinda sucks if it's a disappointment and you can't go back.
I would like the prospect of a new world. Especially because this one is too full, and too polluted, but yeah, human nature, we won't learn anyways, so just wreck the new place.

If I'd go through, I would like to inform my family and take my girlfriend with me.

I would took me sereval minutes to make a decision and when I had decided the portal would be closed.

Your question is wrong! How can one "know" that he witnesses "an interdimensional rift, a "portal to another world", that would only be open within a short timeframe and would not be likely to kill you (although - you never know with these things) but almost certainly would allow merely for a one-way trip..." One cannot possibly know that! First of all, I mean, what does a "portal to another world" look like? Can I know that if I see one?! I won't anwser your question because it's not a question at all! :)

It depend on whether or not there would be people I care about coming with me :)
If not then I probably would not step through. If it was to save my life though I would jump right through in.

How would I know it's a portal? How would I know it's a safe, one-way portal? A spirit/alien/mysterious note told me? I'd sleep it off, if that were the case, maybe they sold me something with a little more punch than vitamin C at the pharmacy.
I'd ponder my sanity long enough for the portal to close, probably. Damn.

Also, in, you mysterious person, you. :)

I'd jump through the rift as fast as I could. I know I have't seen almost nothing of our planet, but if'd get a chance to explore the Universe, I'd go right ahead. A mission like USS Enterprise's or USS Voyager's would have been perfect for me. Just cruising down the Milky Way or such and exploring whatever I would stumble upon.
Of course with rifts such as this one, you never know where will your jump end. It might bring me to a Hellish system like our Earth in DOOM and I would need to fight for your life. It might be a time jump and I could end up in the middle of WW2 so I guess I would get an opportunity to snipe. It could be something typical from our SciFi, like in StarGate series and Outcast game, and I would fight to save the people from the oppresors. But then again I might end up on some great planet, perhaps even The Planet of the Babes :D , and well :D ...

Whatever lies on the other side, this is a step that must be taken, and I am, willing to take it.

Thanks and +1 for the original giveaway, Vestin!

Also, a little promotion to it:
http://www.gog.com/en/forum/general/how_does_one_make_a_gift_aka_gifting_on_gog_for_dummies/post379

Regarding your question, in my experience I always ended up to step through such portals, like it or not. It's sort of an occupational hazard (check my avatar). So the logical answer is: yes. :D

And just in case, a picture: