Had the Mini + Glo for a day now - surprised how small the Mini is: about 0.5" less in length than the Opus, width is the the same, and just as light. Good, crisp screen. Best thing for me so far is that Kobo now have my fav font Caecilia already installed on both models - can alter both weight and sharpness so viewing becomes perfect.
Mini screen quality is as good as the Glo, which to my eyes is as good as the Touch. Page turning is comfortably quick on Mini and Glo - seems to be the same software on both models (apart from the light of course). I've sideloaded 908 epubs and used 47% of memory. The Mini handles them well with not much slowdown in response. On an SD on the Glo and just as good - response seems slightly quicker on the Mini - I suspect using int memory the reason. Both readers come with v2.1.2 software installed but both upgrade to v2.1.4 when registered with Desktop. I like the Home page a lot - no ads apart from your Wishlist - don't set one up and you won't see any. The Wishlist occupies a narrow strip at the bottom. Shelves works really well on both readers. Software seems much better than the v2.1.1. I have on the Touch. Quite a few small tweaks for the better - there's a book count in Library view - a clock followed by % read at top of page when centre tapped. Chess game in Extras is really good - sadly, not in Mini though.
The Mini will need a cover - it seems so small and light, but it's great to read in bed! It does fit snugly into the padded pouch that Bookeen send out with the Opus. I rate the best 5" reader to be the Sony 350 (with PRS+), next is the Kobo Mini, and then my old faithful Opus. Hope this helps you 5" fans.
PS... forgot to mention the back is removable and you can clip on various coloured backs - might be important to the fashion conscious.