I had a quick look, but didn't download it in the end (£2.99 to find out if it might be good).
There are many problems translating from Thai, things that get computers confused. The words for 'I' 'You' 'She' etc. all have other meanings in different contexts, so I'm always wary of claims that online translators work with Thai.
Also, how would it recognise what tones the speaker was using?
I'd also be interested to hear from anyone who's put their £2.99 down and tried it, sorry I wasn't more helpful