The review is in Spanish , but here is a translated conclusion:
“Pros 🙂
+ Simple and intuitive design.
+ Lots of features all in one.
+ Fluency and speed conversion automatically.
+ Is free and includes no advertising banners.
Cons 🙁
– It is only available in English.
– Maybe the interface has become somewhat outdated.”
Please see the full review:
http://www.isenacode.net/2014/07/converter4u-conversor-de-unidades-de.html