AndrOpen is just a third party ported version of OpenOffice for Android. The interface is horrible and working with large files is a Nightmare in the Daylight!
It's an 88 MB app...that'll take some time to download and install. If it even does!! It may just give you errors and fits even trying!
My recommendation is...Stay away from this rubbish. If you are still compelled to find out more you can check for yourself with the links provided below.
On the other hand Libre Office will become available as an alternative sometime in the near future. It was announced in August, but there is still, to this date, no set release at this point.
These apps are really not worth the time and aggravation you'll endure just to have an Open Office.
In my opinion the developers at both Apache and with Libre all missed the boat on creating a desired mobile app. Other developers have already beaten them there, and have won their market share and have better products.
The really better alternatives are to use the online office suites that are integrated with your email.
Google Docs, MS Outlook and Zoho. They all offer better cloud versions of office software than android or other app versions.
If you still need an office app for the Android phone, the best one for sure is Polaris, it even opens PDF files.