Russell Beattie thinks its the best mobile browser.
First, its small and easy to download and install. At 100k, even my GPRS-only Sony Ericsson W800i phone downloaded and installed it in less than a minute. This should not be overlooked – Opera has made the process dead-simple by providing direct access to the download (no registration, or multiple page views needed) and paid attention to the size of the app to make sure theres no bloat. It seems simple, but these two things alone separate Opera Mini from 90% of the mobile apps out there.
Next, the speed of the downloading is incredible. It makes GPRS seem A LOT faster – i.e. actually usable. Not only must they be doing compression and down-sizing of pictures on the server, they must be managing cellular latency really well. Latency is the nemesis for all mobile Internet apps. So where other mobile browsers will be dumb and create new requests to the Internet for each image or file that makes up a web page (taking latency hits each time) Opera Minis architecture allows it to make only one connection to the server and get perceptably huge speed increases as a result. Like I said, Im using it right now to browse around on my GPRS phone, it feels like a handset with a much faster connection.