While watching the only trailer Super Mario 3D World has, the timer maximum is 477 seconds. Because the Mario has already started that stage I am going to assume every stage will have 500 seconds (no science rocket there).  That will be exactly 8.3333.... minutes. That should me long enough as to run almost everywhere you want. 

I also asked myself, Super Mario 3D Galaxy 2 didn't have a timer. How much did I spend on it during every stage? well, I don't have the game with me (i am in college), so I decided to check how much did someone else spent on several stages by looking at some random walkthrough on youtube. I was impressed the guy spent around 8 to 9 minutes playing 10 stages, that includes getting comet coins and the usual star at the end of the stages.

To my conclusion, there is nothing to be worry about. Yes, I can agree to a certain point that the timer can restrict some of our choices, but it also adds some difficulty by doing so. Replayability also. I remember Galaxy 2 being somewhat light on the difficulty. So there you go, what are your thoughs on it?

I never thought the timer was that big of deal, looking forward to the game.

I am on the same side as you. Even its similarity with Super Mario 3D Land is nothing bad at all, the game has sold around 8 millions so far. It was an intelligent decision for Nintendo, after the Wii U sales pick up (hopefully) then they can try something different, in my opinion.

As long as its nothing like New Super Luigi U with that 100 second rush crap

3D Land was awesome, and I'm excited about that kind of gameplay but bigger and with 4 player coop.

that would have kill every enthusiasm about that game for me!

that 4 player co=op sounds very sweet, even more around christmas to build some hype with the family!

If anything they should reduce the timer, that would increase the anxiety of the player. I loved the extra challenge levels in 3d land

^^^ Winner! After KIU, SM3DL is my favorite 3DS game, i'll be enjoying this with my bro and my sis! Hope SMG3 comes in 2015 though! People confuse this series with 3D mario platformers. This is clearly a surperior 2D mario played in 3D (i personally like more!)

Edit: Only 1 problem with this game, the ONLINE! Really could of been awesome playing with you guys to show you how much of a gamer i am

don't push it too hard! but yeah, it all depends on how the stages are designed. We still haven't seen anything about it. That got me really curious!