In short, the Court ruled that the fact that A and B had to travel to obtain abortion did not breach their rights under Article 3 (torture and inhuman/degrading treatment) or Article 8 (right to private life), but there had been a breach of Article 8 in the case of C, who feared that her pregnancy could cause a return of her cancer. The Court was essentially stating that Ireland had breached the Convention by not ensuring the effective protection of rights it was guaranteeing (a doctrine developed in Tysiąc v. Poland, which also concerned abortion), as the Court judged that there was a lack of sufficient means of obtaining a medical evaluation showing that a woman fell within the exception permitting abortion. Since C couldn't obtain such verification, there was a breach of her rights.
The judgment has been covered well by the ECHR Blog and Human Rights in Ireland. The Human Rights in Ireland article is a great brief explanation of the judgment's context in Irish law.
So claims that the Strasbourg Court is interfering in Irish abortion law are simply wrong. The Court just states the Tysiąc v. Poland position that if a state grants rights, then individuals should have adequate access to such rights. In a way, the Court is acting as a court of fourth instance on human rights here: no European-wide right to abortion has been recognised. Neither the Lisbon Treaty nor the ECHR ruling has changed anything regarding Irish abortion law. Not that this stops fundamentalist Catholic groups such as Youth Defence from decrying the judgment as interfering:
"The ECHR has no business interfering in Irish pro-life laws and they have no right to try to scare Irish women into believing that they would ever need an abortion to save their life."
Sadly, there is unlikely to be any political debate or moves for Constitutional amendment in the forseeable future. The current Fianna Fáil government brought in a blasphemy law provided for under the Constitution, rather than remove the Constitutional provisions via referendum, which would have been more in line with 21st Century Ireland. Though Fianna Fáil won't be in government for much longer, the next government's attention will hardly be focused on reforming the Constitution to remove the explicit Catholic ethos and to secularise the state further. So while the country becomes ever more liberal and secular in its attitudes, the entrenchment of a Catholic outlook in the Constitution gives groups like Youth Defence a stronger say than they would otherwise have - to the extent that they can claim their views are the patriotic ones.
On a final note, regarding the treatment of A and B, the Court should have dealt with things differently. The dissenting opinion views the core issue more clearly than the judgment: the Court should have balanced the rights of the mother and unborn child, rather than confuse the issue with the margin of appreciation the state has over determining the point at which the unborn child can be considered alive (the issue in Vo. v France). I'll not go into the dissenting opinion (this post is already long enough!), but it makes quite a convincing argument as to the approach the Court should have taken. Perhaps it is an example of the Court shying away from making politically sensitive judgments at the expense of the coherence of its case law.