I got an RP2 (not plus) when it came out, and while it was a very nice little device for the price, I ended up switching back to using my phone, once I found a way to output HDMI over cable from my phone (it doesn't do it natively, but there's a way) so I could seamlessly transition to a big TV when I'm at home. The performance on the RP2 just wasn't good enough when compared to my phone and a Bluetooth controller.
I kept my eye on the scene for a little while, hoping for something that could do DC, GCN, and PS2 at full speed, since my phone can't quite do that. But despite claims of various handhelds having this capability, none of them really did; in real tests they would just limp along with a few games at around 50% speed or worse. So I got kind of burned out by the hype and stopped paying attention.
I've just had a look and it seems like the RP4 kinda sorta actually DOES handle PS2 to a large degree. So as long as it's got a wired HDMI out, it's not too big physically, and the price is reasonable, I might be back in the market for something soon.