I would say having used it in other BB's it is very buggy for the Storm and not as useful as it was for other BB's. I had 4.1 and 4.2 on the Storm but removed both of them as they don't work as well at the BB browser right now.
Not at all. It works altogether differently and takes a few minutes to master. I'm writing this response in operamini 4.2 on a storm. It's a lot faster than the bb browser and less annoying in many ways, i.e. the helper bar at the bottom not always popping up and down as you use it. Some may prefer to stay with the well-integrated bb browser, but power users who like speed will most likely use opera a lot. --bg
There are some things that Opera won't do. It works very well for most things........but try using these forums with Opera on a Storm. It's great for the first page, but there's no way to get to page two of the posts that I've found. If you click the "2" on the bottom of the page, it'll try to call the number 123456789. The BB browser can use the cursor mode to allow you to select specific things (which works ok once you get the hang of it). Neither is perfect, so I find myself using both depending on what I'm doing.
I tried it briefly, and didn't find it particularly buggy, but it didn't do a very good job of formatting the page to fit the screen and a few other things so I got rid of it. It did seem many times faster than the BB browser, but I almost never use that for anything besides OTA app install, so it's a non-issue for me.
I'd say download it and give it a try yourself. It's free, and it only takes a couple of minutes. If you don't like it you can just remove it.
I didn't find it buggy, it was more of, getting used to it since it wasn't developed for the Storm. It works with the Storm but that doesn't mean too much. I like it to far. Haven't had a problem with it.