For research purposes the answer is probably no. But for 1Ls who don't want to buy Blacks the answer may be yes.
Wex is the online dictionary/encyclopedia available on the Cornell LII website. The dictionary is here; the encyclopedia is here. Most students will find the Wex "all" browse page the easiest to use because you don't need to worry about variant spellings. There is a handy search function you can use if you like.
Why would this work for 1Ls? First, it's free; and free is good. Second, it's simple and simple can be very good when you are starting out.
But for those using the dictionary or the encyclopedia for research the latter reason is exactly why it is not yet suitable for anything but the most simple research tasks. As yet, there is insufficient material to handle any significant research. And, if you did use it how would you cite to it?
Wex works and works well. It does not appear to be the intended to be the ne plus ultra of legal research. As long as you know that, it is a valuable tool to add to your research and 1L study tool belt.