Yup the retail version sold here is locked to SEA region just like the retail L4D2.

The Steam store version of CS: GO is region free.

That's correct. SEA region locked copies of Valve games cannot be played outside of regions like Malaysia, Singapore, Vietnam or Thai. These retail are only meant to be sold inside these countries. Your Steam client will blank out the copy of your game whatever you try to play it in countries like the US, Canada or UK.

The pre-order price for CS: GO was even cheaper on the Steam store than buying retail plus it's region free and you receive a bonus TF2 weapon.

Region lock here means you are only restricted to run and play the game in your specific region you bought the game from. You can still play the game with anyone but the client will check your copy prior to running the game. Region free copies are exempted from this.

As for how does it play compared to the classic 1.6 you can read and watch plenty of the thousands reviews on the web including opinion by longtime veterans CS players.

Local network play and playing on other people servers is still possible. Why would they restrict this anyway? It's still CS.

Another thing to add considered this is on Steam and a Valve title, it uses VAC.

A better question would be, why should most people even bother playing it on the console? considering the player base and the community of former veterans moving on with GO.

It is pretty much agreed among many nothing close come to VAC. It is the best anti-cheat detection and prevention among the industry. It has a very impressive built algorithm that can adapt against any new exploits.

Just name me one system with a similar if not better reputation to VAC. There are none to my knowledge.