First, how the situation looked like in 1992, just before the break up.
1. Majority of Czechs and Slovaks were against the divorce at the time when it was happening. This was the decision of politicians, against the will of majority of citizens.
2. Minority that actually supported the split had very different reasons on different sides of the border.
- In Slovakia, the reasons were more emotional (nationalistic, if you want) - many Slovaks wanted their own state, regardless of what would be the consequences.
- On the Czech side, there were some nationalistic feelings as well, but supporters mostly thought Czech republic would benefit economically: getting rid of the poorer (troublemaking) Slovak part of the federation, thus being able to develop the economy much faster.
In general, there was a strong expectation that Czech republic would come out as clear winner after the break up.

Now, how does this look like 20 years after?
The strange thing is that in retrospect, many more people think that the split was a good idea compared to how many people supported it in 1992.

Politics in both countries developed in two very distinct ways. Slovakia first went through rough period of authoritative governments, followed by very progressive ones (trying to catch up after years of lagging behind) and because of this, the economic reforms actually went much further than in Czech republic, which never had to go through hell of isolationist governments.
At the moment, Czech republic is still doing better economically, but the difference is now probably smaller than it was any time during previous couple of centuries.

Both countries joined European union and NATO, Slovakia (but not the Czech republic) is the member of eurozone, and, unlike for example former Yugoslavian countries, their ties are still very strong and they tend to co-operate on international level (starting from small things like sharing some embasies abroad).

The relations between the nations are now probably better then ever on most of the levels. Most of the Slovaks feel Czech are by far the closest nation to them and vice versa. Slovakia is still the most popular Czech tourist destination, etc...

The important thing is that both Czech and Slovaks now have only themselves to blame for the state of their countries, and they have no choice than to focus on actual problems instead of blaming each other about who is getting more out of the federation.

In summary, my personal opinion (as Slovak) is that the split was beneficial for both countries, although one might easily argue for either of the countries in different areas of development.