I think it's a great start. Perhaps a bit of segmenting/ ribbing on the underbelly and more plating on the crown/head. The plating on the head would help to tie it in more with the current tyranid models (and better explain the burrowing nature). I cant really determine the scale (guessing quite big), but more detail would break up the large smooth surfaces that will otherwise be a pain to paint. keep up the good work.
