I bought my GPD Q9 PSV a year ago, and i use it almost every day. It has very smooth and responsive buttons and analog nubs. The screen is big and very bright, the games look just amazing on the 7 inch screen.
With the original stock rom and dedicated emulators it is far enough for Android, PS1, MAME, NEOGEO, and the 16-8 bit home console emulation with full speed (60 fps). If you want the device more powerful, in order to run PSP, 32X, or Dreamcast games, you need to install Legacy rom, i think.
You wont regret buying it.