Are delay slots unique to mips? They're a pretty significant aspect (complication) that I don't see anywhere else.
Also, the gp register- don't know of any other arch where you need to set something like that up to access global variables. It's another layer of indirection which makes the assembly code harder to read (especially PIC code that works off of the value of the t9 register)
No, several other architectures of that period have delay slots (80s/90s), and modern VLIWs/DSPs still often have them. Sometimes the slots longer than a single instruction.
Also, the gp register- don't know of any other arch where you need to set something like that up to access global variables. It's another layer of indirection which makes the assembly code harder to read (especially PIC code that works off of the value of the t9 register)