I'm not saying the Technics arm is better than an RB500 or 700, but when the drive mechanism and tonearm resonances are controlled and the noise drained out via a platform or plinth, the overall package is surprisingly satisfying.
10-13-11: Audiofeil
I bought a 1210M5G a couple years ago...
However, the stock tonearm is the major drawback of this table. You can change the bearing, isolate the table with fancy devices, re-wire the arm but a lipsticked pig is still a pig.
If you fancy using this arm with any serious cartridge, you're already bottlenecked by the arm.
And when you hit that tonearm performance bottleneck, there are armboards available for mounting a Rega-compatible, a Jelco, or SME tonearm on an SL12x0 series. As much as I like my current rig, my next step would probably be to mount a Jelco or SME arm and still be ahead of the price/performance curve.
The SL1200 was always meant to be a mid-level enthusiast's turntable. It was also available as the SL120, which had an SME armboard instead of a tonearm. I suspect that that's more the way the engineers intended it.