Is a double slip better than a regular point?

A double slip is an X shaped crossover with a difference. That difference being that there are point blades attached to it, so the train does not have to just cross straight over the junction in a straight line, now it can turn onto the track that is converging.

A double slip has four possible routes as shown in the picture (eight if you are counting in both directions). A single slip, however, only has point blades for one of the converging routes and therefore only has three routes available.

Slip points would be used in situations where there is a requirement for trains to have access to a lot of different routes or tracks but in a limited space such as the approach to a station. This very fact is what makes them so appealing to modellers as space is always at a premium.

As for the original question is a slip point better than a regular point? That would depend on why you are asking. From a space saving perspective these points are brilliant and give much more operational flexibility, they look great too, but then there is the flip side of the coin to consider, as is often the case with model railway track-work, the more complicated it is, the more chance there is for derailments and trains stalling. The reason trains stalling could be an issue is because your train now has two frogs (the plastic isolating bit of the points) to combat opposed to just one with regular points. So it would depend on how many pick ups your engines have as to how well they traverse the points.

This would also be something to consider if you are likely to be using some really old rolling stock with wider wheels as these too can sometimes get wedged in complicated point-work.

If you have decided that a slip or double slip is for you, they are available in 00 and N gauges, they can be motorised if you wish and they have an angle of 12 degrees meaning they look roughly the same as an express point, if your model railway is a little more advanced then you can even get slip points in Finescale or with live frogs for those of you that model in DCC.