It depends on what you want to do. Can't really speak for level 1 but in general it is an asset to hold a CFA degree (i.e. all three levels). I think it is particularly useful if you want to work in either corporate finance or asset management. It looked into it when I was working as a derivatives trader but decided that it was of no use for me. For more quantitative jobs - have a look at the FRM or the CQF. I have a friend who just graduated from the CQF and he showed me the course material. It is very good and you really cover a lot of what you would do in a MSc. in Quantitative Finance, even though in less detail. The downside is that is is way more expensive than all the other degrees.

From my research, CFA is generally a very tough course - the pass rate has been known to be on the lower end and dropout rate is quite high(however in saying that doesn't mean you shouldn't do it!)

It would be ideal to complete all 3 levels - it requires alot of commitment (250-300)hrs per level while working. If you are doing M&A at an IB I would be doubtful that you would have the time to do a course such as CFA.

There is wide debate as to whether the CFA is better than MBA etc. - there seems to be a consensus that people who want to do asset management will benefit most from doing a CFA (again there are arguments against this as well) + it shows your commitment to finance.