Wow, some lovely downvotes for making a suggestion. Not sure how two words can be so offensive to people...
Other advantages to Propeller in addition to what you say:
- DIP form factor, easy to breadboard
- Very little supporting circuity needed. Very easy to set up.
- Enthusiastic intimate helpful community on the forum
- GCC available (not an advantage over Arduino but it exists you don't have to use SPIN)
- Pretty high performance compared to Arduino -- 80mhz on 8 cores [tho that doesn't tell the whole story since memory accesses to the shared memory take a lot of cycles)
Other disadvantages:
- Small memory space. 32k of slow shared memory space, only 2k per cog (core)
- New Propeller 2 is taking years to come out and the old Prop 1 is really starting to show its age
I'm not sure DIP form factor is a pro these days - it ups manufacturing costs a lot - unless of course all you are making is breadboards - are there SMT versions available?
Cons:
- Comparatively high price point at $8
- The custom 8-core architecture is more difficult to make full use of
- No other chips in the family (can't flexibly move up or down in flash size / IO / core count)
- No interrupts
- Uncertain availability, and may be nearing end-of-life (this is speculative)
- Programming in C is secondary to the proprietary scripting language SPIN (which has an interpreter in the chip)
Pro:
- The processor is open source under GPL v3
- Multicore architecture makes it easy to create systems that work concurrently
- VGA output
- No interrupts
- SPIN isn't that bad... and assembly code integrates nicely with it