I'd also say that R is better for a number of reasons. I say this having used Matlab for a number of years and having switched to R and I wish I had learned R in the first place. There is blog Abandon Matlab that lists a number of reasons why working with Matlab is sometimes very annoying. Here a there main points why R is more productive for me:
Matlab functions are called with inconsistent syntax across and (within) toolboxes. e.g. if I want to change my classifier in a model in R I usually only need to change the name of the function and keep the call and data intact. In Matlab this usually involves reformatting the data and a totally different function call that I have to look up from the docs.
R has better data structures I think the only workable construct in Matlab is the basic array and working with anything else than numeric variables is awkward, further you can't call the columns by name, but you have to use the index of the variable (hmm, was it column 33 or 34, that I wanted to plot ...) . You can't beat the data.frame in R!
R has a lot of useful packages for ML
Matlab has no named arguments to functions
Finally if you work a lot with matrices and find the Matlab syntax nicer then check out Python with Numpy and Scipy. Python also has some nice ML libraries such as PyBrain. I'm not going to compare R and Python here, because thats an entirely different question :)
