Touted as a browser for phones with low memory, the Opera Mini browser is compatible on over 3000 phones and boasts 61 million users. Today, Opera introduced Opera Mini 5.1 which is going to replace Opera Mini 5. For phone users of limited memory, it is probably to your advantage to upgrade to the latest Opera version because it will help your phone access the web quicker. If you have a smartphone or a high end device, upgrading to 5.1 is not necessary.
The new update introduces a new skin which allows multiple pages to be open at once, increased scrolling speed, and overall a more efficient and faster browsing experience. Since Opera compresses all web data by 90% before delivering it to the phone, Opera Mini 5.1 would be quite useful with limited memory phones such as the Nokia S40 series. Data compression will also decrease the amount of megabytes you send and receiving, which is definitely helpful to users who have a data cap. Phones such as the Nokia 5130 XpressMusic, Nokia 6300 and Nokia 2700 are advised to upgrade the Opera Mini 5 browser. In addition, phones will smaller screen sizes such as the Sony Ericsson K550i and Sony Ericsson W810i are advised to upgrade as well.
Via [Opera Press Release]