Olive Trees app lets me do a wonderful thing: carry the Hebrew Bible (Biblia Hebraica Stuttgartensia), the Greek New Testament (Nestlé-Aland 27), and a couple of English translations around in my phone. I can display the original language in parallel with an English translation. I can do searches in them. This is all very handy. The Hebrew and Greek fonts are well done and display well at different sizes.
It should be clear that there are some limitations. Although the Hebrew and Greek texts are critical texts, they do not include the critical apparatus. So I cant check textual variants. Also, the texts dont include morphological analysis, which would often be helpful.
Olive Tree has a tendency to download texts I dont want (mostly commentaries and "helps"). These take up space on my phone. The Bible Maps are not very detailed and cannot be searched.
The software is rather expensive for an iOS app.