I often like to compare the position of the Welsh Language with minority languages in similar situations on mainland Europe, particularly in Spain. But one thing that uniquely qualifies the Welsh Language is the level of negativity associated with and directed at it. It's normal for Spaniards outside of Catalonia and the Basque Country to make negative remarks about the Basque and Catalan languages, or for immigrants (mostly Spaniards from Andalucia) living in or around Barcelona to do so, but this resentment is far from being as prevalent as that which occurs in Wales. What is more, this negativity is a manifold one: it is not just the negativity of the English, nor that of non-Welsh speakers among the Welsh, but also that of Welsh speakers themselves.

The resentment of English people towards Welsh is at best based on ignorance, and at worst beneath contempt and therefore not fit for intelligent discussion. That of the Cymry di-Gymraeg (Welsh people who can't speak Welsh) is more complex: in the South it is both a resentment fuelled by percieved elitist attitudes among middle class Welsh speakers and one actively encouraged by successive pro-Unionist Labour Party governments both on a local and a national level. In the North it is to a some extent the bitter spawn of English colonisation, but it is also caused by a percieved connection between the local lingo and the dire economic situation prevalent in the area (ie "This place is crap, therefore Wales and the Welsh Language are crap too").
Some of this has seeped into the consciousness of Welsh Speakers themselves, who consequently decide to abandon their language and cut their children off from their linguistic inheritance. Such attitudes are hard to find amongst the Basques. The Basque Country has an almost identical ratio as Wales in terms of who speaks the native tongue and who doesn't. Yet there is little or no negativity felt by monoglot Spanish speakers towards Euskara, and they are quite happy that their children are educated in that language (Then again, the Basques have jobs).
But there is another aspect to the negativity of Welsh speakers towards their own language: for many, it is the language one uses when talking to friends, family, and old acquaintances, but it is not to be used with strangers, even when they're speaking to you in Welsh! This can be both an obstacle and a major pain in the arse to learners!
As i have said, the resentment of the English isn't worth talking about, but the overcoming of negative attitudes amongst the Welsh themselves is of vital importance to the success and survival of the language.