My family has 3 Kobo Wi-Fi's and 1 touch. The only big issue we've had is the rubber button separated on my own wi-fi, and most small things usually get addressed in firmware updates.. The 10 year old can't put hers down, and the wife hasn't had any issues when she uses hers. I encountered the storage issue once, but I think it had more to do with a particular book (Which is still causing me problems, although not on the kobo itself...).
Like others have mentioned, I think most peoples frustrations aren't actually with the device itself, but with the general support that Kobo's customer service provides. Yes, they are a small company, but that doesn't excuse the fact that their support is very inconsistent, and most reps seem to have very little knowledge of the product they are supposed to be supporting. If anything, being smaller should make it easier to get processes out to their entire team.
That said, like any product, you will always have a much more vocal angry minority than the quiet happy majority posting here; Forums weren't generally made to discuss what a good experience people have, but to try to find help to the problems they might be having and work arounds to said problems. People are going to be even more vocal when they know the company is trolling the boards for issues.