depends on the technology but if software/internet, no. In innovations that evolve overnight, concepts of IP and needing to legally protect an idea from your clearly evil intent to put them out business, are misplaced. In my experience, they drastically stifle success by preventing the engagement of advisors, consultants, and even early evangelists who can make or break a venture.
A networking app? You can't have a conversation in your startup community without running into someone else who has a networking app. The NDA puts YOU at great risk for that reason alone... burden of proof that you did not share, anything, ever, falls to you - how can you do that?? Especially when networking apps are a prevalent as lawyers :) You will have a conversation, unwittingly perhaps, with someone they consider a competitor/threat and you can't be accountable for what is OK to share and what's not.
Grain of salt. Unless, they are completely clear and detailed in the agreement about what you can't discuss. Not "financials" but specifics so that only when that information is public, is a question of your confidence appropriate.
Frankly though, the whole idea just sets the wrong tone and prolific startup ecosystems have largely abandoned them. They are essentially saying, we don't trust you, so sign this so you are legally accountable to us for anything that you say. Why would you want to work with that?? More importantly, what do they have to hide? Ideas are WORTHLESS, and only building and discussing them can create scale.
Don't misunderstand me, I'm not saying you don't have to earn their trust and that they shouldn't have an expectation of it; and I'm certainly not saying you want to avoid an NDA so you can go blab to the hills. Rather, it shouldn't be needed and it only creates risk, for you.
Why did I start by asking about the technology? Like I said, software/internet moves FAST. I'm sure, no matter how brilliant they are, there are 10 other ventures around the world building essentially the same thing and tomorrow there will be 10 better ideas. There's your risk. When one of those emerges, is known, how do you prove, with the extensive network you have, that you never said anything to anyone, resulting in the traction of those others???
Not so true though of hardware or health related ventures in which there is long lead time to bring ideas to market, or industry validation/certification that has to occur. In those cases, NDAs make some sense.