Question: What are the new features/updates are available in Selenium 3 as compared with Selenium-2.0?

What are the impacts of using Selenium 3.0? What are the recent errors which were found in Selenium 3.0? You can share Pros and Cons/your experience with the use of Selenium 3.0.

Answer: 
Good question, everyone should aware of the new updates and features in Selenium 3. 
As of my experience Selenium 3 has lots changes made in configuration/setup level. Even though we have to use GekoDriver for launching Firefox driver. There is also some browser compatibility restrictions are applied in Selenium 3 like Firefox min version must be 48. 

* For WebDriver users, it's more of bug fixes and drop-in replacement for 2.x
* Selenium Grid bug fixes are done as well.
* Selenium project will not actively support only the WebDriver API.
* The Selenium RC APIs have been moved to a “legacy” package.
* The original code powering Selenium RC has been replaced with something backed by WebDriver, which is also contained in the "legacy" package.
* By a quirk of timing, Mozilla has made changes to Firefox that means that from Firefox 48 you must use their geckoDriver to use that browser, regardless of whether you're using Selenium 2 or 3.

You can read more [here.](https://saucelabs.com/blog/selenium-3-is-coming)

[Reference Link2](https://saucelabs.com/blog/selenium-3-is-coming)
Moving `Selenium 2` to `selenium 3.0.1` is bit easy take less effort 

[Code Changes](http://seleniumsimplified.com/2016/10/upgrading-to-selenium-3-with-my-first-selenium-project/)

One of the biggest change is that the old Selenium Core libraries will be dropped in 3.0. The focus will shift completely to the WebDriver API. 
For the last six years it has been advised to switch to the newer WebDriver APIs and to stop using the original RC APIs. With Selenium 3.0, the original implementation of RC has been removed, replaced by one that sits on top of WebDriver. For many users, this change will go completely unnoticed, as they’re no longer using the RC APIs.

Firefox is only fully supported at `version 47.0.1` or earlier. Support
for later versions of firefox is provided by `geckodriver`, which is
based on the evolving W3C WebDriver spec, and uses the wire protocol
in that spec, which is liable to change without notice.

The `WebDriver API` has grown to be relevant outside of Selenium. It is used in multiple tools for automation. For example, it's used heavily in mobile testing through tools such as Appium and iOS Driver. The W3C standard will encourage compatibility across different software implementations of the WebDriver API.

[W3C Working Draft](https://www.w3.org/TR/webdriver/)

There are many updates please have a look

[Change Log](https://raw.githubusercontent.com/SeleniumHQ/selenium/master/java/CHANGELOG)