Does your idea have to be "unique" for your startup to be successful or you can be just "+1" to the market, execute well and still succeed?

You are more likely to fail if you are "unique".  Its safer and easy to clone existing businesses and incrementally improve them.  First movers almost never understand the market as well as their competitors and are usually annihilated by the later competition (which only has to improve their product or exploit a new marketing channel).

Creating a new market and holding it is the most difficult you can do, where as incremental improvement is much easier and has comparable financial advantages.

Google was not the first search engine.  Google did not invent search monetization (Overture did).

Facebook was not the first social network.  It was a clone of HouseSYSTEM and myspace.  Myspace was a friendster clone.

Zynga did not invent Farmville, they copied the game almost to the pixel from Farmtown.  Farmtown was a copy of the Chinese game HappyFarm.

The iPod was not the first mp3 player.

Microsoft Windows was not the first or even the best GUI OS.  In fact it was technically inferior to its competitors, but won the standards war because Microsoft had a better understanding of the market and the nature of computer standards than IBM or Apple.

And so on.  Its rare that the first company into a market is the company that becomes the dominant player in that market.  I have never seen it happen in the absence of a government granted monopoly.

Your product should be designed to satisfy a validated demand that consumers have, but perhaps in a new way, or with a new technology; for instance, people have been watching video since the 1960s, but Youtube enables them to satisfy that need over a new medium (the internet/web-browser).

If there is not a product in a market (or atleast an extreme shitty product), the reason is generally that there is no demand for that product.  However, concepts like tablet computing and Groupon were tried several dozen times and failed before they were successful.

Personally, I am big fan of improving existing services, exploiting superior knowledge about your market (such as using better marketing strategies or distribution methods) and market segmentation.  Market segmentation is great strategy for grabbing your competitor's customers and potentially being able to achieve higher margins

Posted in: business,entrepreneur,growth,ideas,startups,stratups