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I have been reading lots of discussions around the Scrum Alliance and its certification process. Does taking a two class make you a good Scrum masters? For an answer to this question, I asked some of my friends who have been great scrum masters.
The general opinion was that while the CSM class does give the basics of Scrum, it completely misses the ball on the “Human factor” involved in being a good Scrum master. Some of the best scrum masters seen are not certified but certification does help. The great thing about the CSM class is the interaction with others much less the certification part. Many times scrum masters learn by doing trial and error on Scrum basics and in doing so they end up causing a lot of damage to the team.
By going to a CSM or for that matter any training class , the interaction with the instructor and others in the class will get you going on the basics. I am an Agile coach and often play the role a scrum master. The toughest part in being a scrum master is not Scrum, it is being aware of what to do and what not to do in a team.
Every time I take the role of a Scrum master and coach Scrum masters, I always tell them not to apply the same rule to every team. Each team you will facilitate is different. As far as certifications go they are a nice to have tool , but that should certainly be not the criteria to hire a scrum master.
Along with it try to see if they pass the CFROC Test.
Are they committed to the team, Can the keep the focus on Scrum and distance themselves from the politics, Can they respect themselves and thier team members,
Are they open enough to help the team with whatever the team needs without taking any sides, Are they courageous enough to stand up to the team and protect them.
BTW this is spoken about in the CSM, but leaning and doing are two different things.
Agile Practitioners Guide 
does a 4/5 year course and engineering diploma automatically produce a good engineer? I had seen engineers who had graduated from good schools and good in theory but aren’t good in real-world practice.
does microsoft certified professional certifications automatically produce a good developer? I had seen microsoft certified professionals who writes crappy and disorganized codes.
it’s almost the same with this CSM.
learn the theory, then perfect through real-world practice.
That’s a tricky question, and it certainly can’t. If you are not the right person for that job, certification won’t help.
On the other hand my experience is that a training with a good Scrum trainer can boost your understanding of the Scrum philosophy and give you the kick to practise an excellent scrum process. When I started with Scrum we used some books as main guidance and I always was wondering what’s the special thing with scrum, since we did not understand the basics as for example to build a team which takes responsibility as a team. Or make the process public by using a plain white board, not software in the first row.
Yes, I would recommend to take a training. The certification is just a sign that you did that.