I've had a few hours using the beta and I have to say I'm impressed with what Opera's done. This new version of Opera Mini has the feature set and rendering quality of browsers like Nokia's Webkit, Opera Mobile 8.65 or Safari on the iPhone and it's faster too. Unlike those browsers which only run on $500 Smartphones, Opera Mini works on almost any phone including $30 prepaid phones and the "free" phones you get with a contract.
There's been a lot written already about the new features in Opera Mini 4.0 so rather than repeating what others have said I'm going to focus on my own experiences. At the end of this piece are links to some of my favorite Opera Mini 4.0 reviews.
My main phone is a Boost Mobile Motorola i855. It's a great phone in many ways with a nice screen, stable implementation of Java and unlimited mobile data for $10.50/month on prepaid. But loading software on this phone is bit of a challenge because everything has to be side-loaded from a PC using a cable and a developer tool called iDenJAL (instructions here). Opera doesn't provide a link to the beta software on their PC web page but it wasn't hard to find out that the files I needed were:
Those long filenames are a problem as iDenJAL requires filenames in 8.3 format, so after downloading the files you have to rename them to something like mini40.jar and mini40.jad. The .jad file contains a reference to the .jar that needs to be changed. It's just a text file so you have to edit it and change the "MIDlet-Jar-URL:" line to match the new short name, i.e, change
to "MIDlet-Jar-URL: mini40.jar"
Once you've done all that, just install the .jad with iDenJAL (the .jar will be installed too but that happens automatically when you install the .jad) and start enjoying Opera Mini 4.0. I've made the modified files available on the WapReview Download Page for your convenience.
I sent a couple of hours browsing with 4.0 and it's pretty slick. The "big" feature is what Opera calls "PC View". It's like Nokia Webkit's "Mini-Map" and the iPhone's "Surf and Zoom" - a miniature version of the full desktop web page that you can scroll around on using the direction buttons to move a mouse pointer to find an area of interest (Tip - use the 2, 4, 6 and 8 keys to move the mouse quickly) . When you find an area you are interested in and click, that portion of the page is blown up to a readable size. The zoomed view is also scrollable in all four directions so you can keep reading down or across the page without going back to the miniaturized navigation view.
There's been some criticism that PC View is a gimmick and not really useful, that Opera's previous small screen rendering does everything needed to make PC sites usable on mobiles. In truth, I used 4.0's small screen rendering (which Opera now calls "fit to width") for most of my browsing. But I did find "PC View" perfect for sites that don't put main content first in their markup. A perfect example is TamsPalm, one of my favorite tech blogs, which using "fit to width" requires endless scrolling though sidebars, ads and the "Shoutbox" before you finally reach the actual blog post at the very bottom of the screen. PC View is so much better for this site. The images above and below show how it works. Using PC View it took just 5 clicks to get to the content, the old way using fit to width took an incredible 110 clicks to scroll down to the post - now that's a big difference. I'd expect that I'll be using fit-to-width on about 95% of the sites I visit, but for the 5% like TamsPalm, PC View is a godsend. And it only takes 2 clicks to switch between PC View and Fit to Width.
Opera's also made huge improvements in the area of CSS support in 4.0. Font sizes, numbered lists, bullets, borders and a lot of other style elements that were discarded in previous versions of Mini are now rendered just as they are in a modern desktop browser
That's not to say that Mini 4.0 is perfect. Just remeber that it's a beta and there will be bugs and missing features. There's no RSS reader yet or support for secure sites. There are quite a few cosmetic rendering bugs but the most serious problem is that cookies keep disappearing, even in the middle of a session, which makes browsing any site that requires a login extremely frustrating. On the positive side, 4.0 seems very stable, at least on my phone. I had no crashes or hangs whatsoever. Update 25-Jun-2007; the cookie problem is fixed, logins to Google, Yahoo, Bloglines, etc., persist as they should. It's a server side fix so re-downloading the beta isn't necessary.
Here are some of my favorite posts on Opera Mini 4.0 from around the blogosphere:
OS News - All Hail Mobile Browsing: Opera Mini 4.0-beta Released
Opera Watch - Opera Mini 4 beta released; includes desktop-like browsing capabilities
Palm Addict - Opera Dimension (Mini Beta v4): Fresh look, same old bugs
Charles McCathieNevile - To be-, or not to be-ta? The mini question
All About Symbian - Opera Mini Beta Now Available
Russell Beattie - Opera mini 4 and The Web as the Mobile Killer App