Shoul I be concerned about apps taking my private information ?

It's becoming a bigger concern, for sure. Your best defense: Watch app permissions and don't download apps if you don't want them to get your information. Facebook (not surprisingly) is notorious for this, but many other apps are starting to collect everything from your location to your phone and email. My personal preference is to keep my app load small and not turn anything on that I don't want to track me.

It also helps to check the settings on any app you're suspicious of and make sure you turn off any options like "track/report my location" and so on. Sometimes logging into the app's site on a computer (e.g. Facebook dot com) will give you more options you can turn off.

Thx Alot, but if the apps does take my private information what can of damage can I expect besides spam ??

Depends on what information you're talking about. It's highly unlikely that an app downloaded from Google Play or any other legitimate source, would end up stealing truly sensitive information like bank account numbers and so on. That would be malware, and malware is highly uncommon unless you download apps from unknown/untrusted sources.

Odds are if an app does collect your private information, it would just be for ads and spamming, but even that is rare. Protecting your private information like location, contact info, and so on, is mostly just a matter of paranoia.

You should be very cautious while the application ask for the permissions as there are various application that takes unnecessary permissions like and gain they might cost you a lot, like if you have saved passwords in messages and you installs an application that asks permission to access all your messaging activity now if you give access to the application your security might be at risk now because you never know who's on the other side reading your details !!