I know that a forum is not necessarily representative of the wider user community, but there does seem some agreement on a lot of these niggles. It's baffling how Humax clearly went that extra mile to create the device, yet are content to take "What the hell, they're selling" attitude to mods and to customer perception.
I would use the word 'awkward' about some aspects. Things like losing sound and picture when you press Guide (until you discover that getting there via Schedule 'cures' this!). Having 2 or 3 seconds to key in channel numbers is another, also the way some menus respond to End, some to Back, and some to both. The list goes on - these are not nice-to-have extras, they degrade the user experience, to lapse into corpspeak.
And neither amateurish or inexcusable are strong enough words to describe the daftness that happens with red button, iPlayer, and the black hole inbetween. What's so galling is that, just like the box overall, the bits that are good are great!