Netgear Night Hawk M5 (MR5200): disappointingly unreliable especially given the cost.

I purchased an MR5200 a little while ago and I've been fairly unimpressed with its price to performance ratio.

• The UI is slow and occasionally unresponsive.
• The WebUI is occasionally extremely slow (minutes to load), and/or loads incompletely.
• "Passthrough" mode is extremely unreliable. I had to stop using it. It seems to make the device crash.
• The on-screen keyboard is difficult to type on: keypresses are offset, so I have to type a little off from where I the keys are displayed, or tilt the device at a weird angle to make them seem "right". Typing is sometimes very slow as well, with a second or more between keypresses and the typed letters appearing.
• It sometimes gets confused and tries to roam onto forbidden networks, and cannot be convinced that it should not do that (switching to "manual" and choosing the right network does not work).

Is there any way to fix this thing? Any alternative firmware for it?