In comparison to other vocal synthesizers, Alter/Ego is less user-friendly, with most of the features sort-of hidden, and creates less realistic results. However, it has a unique sound that makes it worth trying out. Also, it's free. Just, remember to space out the notes to allow the pronunciation and phonemes to render correctly.
Alter/Ego is based on the award winning technology featured in chipspeech but instead of targeting Vintage voice technology, it focuses on more ‘modern’ (1990+) singing synthesis algorithms and research.It is specially tailored for musical needs – simply type in your lyrics, and then play on your MIDI keyboard. It’s a true synthesizer, the sound can be extensively modified for easy and expressive performances. And more importantly it is FREE!