I've received the S601 and here are my impressions.
This is in the perspective of a retro game player.
1. The DPAD, is, unfortunately, the weakest link in this package. It is actually 2 pieces (UP/LEFT, DOWN/RIGHT), and allows you to simultaneously press DOWN and UP (and LEFT and RIGHT). Also, the buttons are spaced further apart than in the JXD5000 - which is pretty bad for a dpad which isn't a single piece. I'm giving the D-pad a 4/10 here. The shoulder buttons are loud but provide excellend tactile feedback, and seem to be microswitches, as are the four option buttons. The d-pad and 4 primary buttons are the rubber-dome type. Of the 3 units I own, the Dingoo A380 has the best dpad.
2. Based on the photograph posted here earlier, the nub hardware really is 100% analog. That picture shows a resistive track layout, with a voltage sensing line. It almost certainly gets fed into an ADC on the board. How the driver exposes it to the OS may be another issue entirely, though.
3. USB, video, and headphone connectors come out on the top of the unit instead of the bottom. This is a +1 for intelligent layout.
4. Like the JXD5000, only 1 speaker. Like the JXD5000, loud enough for most purposes. I have an A380 and stereo output doesn't mean a whole lot without headphones on a portable like this. No points docked, but no points added.
5. The touchscreen is resistive. There is no stylus included with the unit. It's good for a resistive touch screen. I didn't buy this to play Android games on anyways, and it functions acceptably for launching and utilizing the emulators. If you really want to play touchscreen games, this is NOT the unit for you, look for a capacitive unit.
6. The screen resolution is odd, but ideal for running emulators of older systems. Screen brightness shifts on vertical rotation. Looking straight down at the unit produces an acceptable display. Even holding this unit vertically, the display is tons better than the Dingoo A380, although not as nice as the JXD5000. The screen is recessed, which will help prevent scratching.
7. The stock emulators work very well with the games that are included. Which are (as usual) almost all chinese. Frameskipping and limiting seems to be working fine. It includes a disc which I assume is a DVD with more chinese games on it. I tossed the DVD out, rooted the unit, and installed the Android Marketplace. You can surely use the stock UI (the included menu program will automatically take snapshots of the screen when you exit the emulator if no screenshots exist) if you just want to use the included emulators. It comes stock with NES, GENESIS, N64, FBA, and some android games. TigerMAME (which seems to be a port of FBA) works 100x better than MAME4ALL on the Dingoo A380, and works better than FBA on the DA380.
8. QC seems a little lax, the power LED on my unit doesn't light up. The right shoulder button needed to be worn in before reliably registering (and I fear for its longevity because of this).
The JXD S601 gets an 8 out of 10 overall for retrogaming.
The software and underlying hardware are finally up to the task of emulating the older consoles.
The screen quality is very good for displaying those old games.
The unit size is a compromise between the DA380 (which is really portable) and the JXD5000 (which with a 5" screen you need a rather large pocket to tote it around). The JXD5000 is hands-down a better portable movie player due to screen size, resolution, and display quality.
Rooting the unit, and enabling wifi allows you to use and SMD client to download ROM images directly from a network share. The speed wasn't outstanding (pulling around 750K/s when using AndSMB to download stuff), but it was convenient. The USB -> SD card implementation is finicky (seems to take half a minute or more for the drives to mount), so I recommend using an SD reader on your PC to put images on your card if you have to transfer a lot of files.
It would be a 10/10 retrogaming unit if they would put a good DPAD on it instead of what we have here. Even the JXD5000 had a 1-piece DPAD which although not the best, was certainly acceptable (and would have brought this unti up to a 9/10).