No such thing as a V6 selespeed, V6 has a electronic four speed auto box with a manual shift option. Seles are a normal gearbox & clutch with a electrohydraulic actuator to operate the gear and clutch operation
I was just about to point that out, thanks for getting there first
On average I'd say that Selespeed makes a smoother job of the gearchanges than an average driver. It can't slip and slide between the ratios like an automatic does (it's just not possible) but when working properly, progress can still be satisfyingly smooth, especially when married with the good torque characteristics of the 2L twinspark.
Selespeed gives you the advantages of a manual transmission without the disadvantages of an automatic. As a bonus, you never have to deal with a horribly-notchy gearshift ever again. If your hands are tied up with something, punch 'CITY' and it takes care of itself. Can't do that with a manual transmission - instead you join the motorway at 7000RPM in second gear because a drink has tipped over (no cupholders) or the wing mirror's fallen off, or some other calamity...
And when you take into account that most manual-transmission cars are going to need a new clutch at some stage, the maintenance requirements of a Selespeed are about the same as for a manual (don't forget there is standard gear oil in the gearbox, which I prefer to change just as I would for a manual).
Selespeed does like to be hooked up to a laptop now and again to adjust the clutch and check that all is well. A ten-pound OBD cable and some (possibly free) software, and you can do that yourself. If the thought of doing that frightens you, then perhaps Selespeed is not a good idea.
People that say the system is complicated really ought to consider how a conventional automatic works - they're very complicated and the bits are buried deep inside (think of the infamous Subaru solenoids) - and I'd wager that the overhaul cost to get a conventional auto back on the road will be a lot more than for a Selespeed. Smaky has the skills to zero in on any problem (he wasn't joking when he said you'd be OK because he's there
For instance, the module that sits on top of the gearbox and contains the hydraulic actuators, electrovalves, sensors, and pressure accumulator is called the 'Actuator'. People that don't know Selespeeds often replace that whole module at a huge cost. In fact a number of the parts are available separately and they really don't all fail at once. A 147 I worked on had one faulty gearchange position sensor (a plastic potentiometer) causing an intermittent loss of gears. I took the sensor off, split it open, and cleaned it - no real cost there and the car's been fine for months.
So take your pick, but I'm in favour of the Selespeed myself. I like manual transmissions but they don't give you the convenience of the Selespeed, plus they also don't last forever (I have a 164 in my garage that needs a new clutch after someone else abused it...) I don't like conventional automatic transmissions because of the power loss (sluggishness and increased fuel consumption) that they inevitably cause. And I don't like CVTs because of the way they take a few moments to wind up...