It is an understatement to say that Alan Johnston liberation (without assault) is a major victory for Hamas. A victory on the international scene that it has began using on all channels at its disposal. Fair enough, we have to acknowledge that it has succeeded where Fatah was not able to do anything. Furthermore it has begun to restore (its) law and order in Gaza. It is no small feat, even if this has cost already many lives, mainly of Fatah members.
But there are other aspects to this. Hamas is claiming that Fatah is responsible for a situation where clans and mafias (such as the one which was holding Alan) were allowed to freely carry weapons and impose their own will. It is certainly true in a way. Fatah never really opposed the clans or the different militias in Gaza or in the West Bank. In some cases, it actually created or encouraged them. This said, it is a very ironical claim from a party which is actually arming a militia itself, outside of any legal process (if this has any meaning in the Palestinian Territories). Worse, this party, Hamas, has not hesitated to use this militia to fight physically "official" Palestinian security services. So it is clearly a sad case of bad faith from Hamas.
Let's not be too naive. Hamas, because it is less corrupt and more disciplined, also more fanatical than Fatah, will probably succeed in Gaza. But at which price will this come? It is pretty obvious that the Islamic Law will be applied (in whichever local Hamas oriented interpretation...). It is probably better than no law at all, in a sense, but it is a very bad thing for a big part of the million and a half Gaza citizens: women, Christians, secular Palestinians. Let's also not forget that Hamas is still a terrorist movement. It might show a nice face from time to time, but the fact is they never hesitated to use suicide bombers, slaughter of innocents, etc., sometimes just to make a point. OK, let's be fair in another way, their opponents are barely better (and Israel has not shown a lot more respect for innocent lives either).
And there is a third party that can still play a very nasty game. To continue "exist" in a political sense, Islamic Jihad will have to show some muscle pretty quickly. They are present in Gaza as well as the West Bank. I would not be surprised if they try to create some trouble in Gaza (to test Hamas new power) and in the West Bank... How Fatah, Hamas and Israel will react to this (end interact together) will probably be the key to Palestine's future.