I work with PSOC on a daily basis.
As a general platform they are not good, by most typical metrics they totally suck:
-banked memory,
-3MIPS @ 24mhz,
-power hungry.
Also:
-it has poor documentation,
-small user base. psocdeveloper.com is the main forum about psoc and this forum has more activity on it than that,
-no onboard ICE. You need to purchase a special debug version of the uC for debugging,
-debugger + special chip costs $400 USD,
-no GCC, up until about 4 months ago the only C compiler was ImageCraft C and that was total garbage but it was cheap @ $100. Now there is Hitech C, which is very good but it costs $1k.
-I have ran into a few bugs with the development software and the uC.
The biggest thing that rubs me the wrong way is that those uCs look like they have lots of flash space. I use the Cy824894 and it has 16k of flash, 16k looked great and I though I would never get close to using it all, but once you configure all the analog and digital blocks I had only about 9k left. Immagecraft C compiler could not optimize for sh*t so basically I ran out of flash space. I use Hitech C compiler and that saved the project.
The next biggest concern was user community, I prefer AVR just because of the huge user community at
http://www.avrfreaks.net, I can ask a question go to the bathroom, come back, and I have several answers. On psocdeveloper.com there is very little activity. PSOC is much more complex than a typical 8 bit uC, so it makes user community all that more important.
For smaller projects where space and cost are key, PSOC is probably the best choice. No one else has those programmable analog and digital blocks, they offer so much flexibility, almost too much flexibility. The programmable blocks are so good that I am willing to put up with all the bad stuff I posted previously.
I hear that by the end of this year a new generation of PSOC uC will come out with an updated core, one version will have an ARM core. With that PSOC will dominate the market if they can get their act together WRT to documentation and refine the dev tools.
I regret using PSOC for my project as I would have had 10x less work if I had used AVR. The only saving grace is that I will have a jump start when the new generation of PSOC devices hit the market, but they were supposed to hit the market a year ago.