Been using the beta for a while
Beta 5 is a welcome and vast improvement for Android, less so for Maemo. The Maemo version works, but seriously chugs.
This beta does fix one very important bug - in previous versions, when you moved the app to the SD card, it didn't move your user profile, so that would eventually fill your free space with cached content. When you upgrade to beta 5, refresh the SD card install and that will be fixed. The install seems smaller in this version too, down to around 12MB on my phone, before user data.
Beta 5 on Android, from using it this morning, is also a LOT faster than previous versions. As fast as the native browser? Nope. But fast enough to use, and if you value Firefox's functionality (sync is worth it for me), it's a nice little system.
BTW, the tone of the article, especially the headline, seems to make out at first like this is a final release. I know you mention it's a beta, but the headline and intro don't come across that way. Just my 2p. Anyway, recommended upgrade if you're with the betas already, and if you haven't used them yet because they just chuffed way too much (and I agree, they did), then give this one a shot.