Sounds perfectly normal to me!!! DS was always really ahead with his speech, whereas DD1 was quite slow - compared to him anyway (and that had us a little concerned!) but when she hit 2 - she's just exploded with words and you can understand nearly everything she says now - plus she mimics a lot more now.

DD2 just turned one and she is looking like another one like DS - she can already say bye, dad and mum.