StoneScapes is a PebbleTec alternative. It is definitely no smoother than PebbleTec brand it is simply a different manufacturer (think Coca-Cola and Pepsi). PebbleTec is a brand name, they are the inventor of the process, and as such there are some definite advantages to using their product. There are also some good alternatives that can be slightly less expensive like StoneScapes. I personally use both products regularly on pools that I build.

PebbleTec and Regular StoneScapes are definitely rough! Properly troweled they will smooth out, but they will never be absolutely smooth. Mini StoneScapes is definitely smoother than regular, BUT that does not mean that it is smooth... PebbleSheen is similar to Mini StoneScapes excepts that it is diamond polished the following day to smooth it out even more. If you like the look of exposed aggregate finishes, then this is probably the best alternative for the smoothest finish. Just make sure that you are using an authorized PebbleTec installer!

Another alternative you may like to consider is BeadCrete. It has a similar look and feel to PebbleTec, yet it is much smoother, because it uses glass beads rather than small pebbles. The glass beads are much smoother (think little marbles) without the sharp corners inherent with rocks/pebbles.

I personally am planning to install quartz or PebbleSheen in my own pool when I build it. The difficulty with these surfaces is that the startup process is often not done properly, and this results in an uneven surface appearance. The beauty of quartz/Sheen is that you have a surface that is significantly smoother than any of the exposed aggregates. Quartz though can become rough if not properly started up. But unlike pebble it is still much smoother. I like to compare it to 200/400 grit sandpaper...

For the most smooth surface available, you can consider Hydrazzo. It is more expensive, but its fully polished marble surface is by far the most elegant and smoothest of the non-aggregate surfaces.

I noticed in another discussion the option of glass tile was floated... PLEASE be very careful if you are exploring that option. We install glass tile, and I can tell you that the waterproofing alone should be about $40,000 for a typical 15x30 pool (450 square feet). Anyone claiming that they can tile a pool for $30 per square foot is not following the TCNA (Tile Council of North America) standards for installation. It is not uncommon for all tile pools to be well in excess of $100,000 for the tile installation and material alone...

My recommendation for you to explore would be in this order:
Hydrazzo (Aquavations)
PebbleFina (PebbleTec brand)
Quartz (QuartScapes, SGM or another reputable manufacturer)
PebbleSheen (PebbleTec brand)
StoneScapes mini
PebbleTec/StoneScapes regular

One final thought...

We often install mini pebble in the spa, and regular pebble in the rest of the pool. The reason is that in a spa is where you have the most intimate and continued contact with the material, so it is nice to have the smoothest option available in that area.

Best of luck!