hello Alfa Cam,
you probably read my thread about buying an 2003 156 JTS selespeed, which i purchased in march this year. I can tell yo that these newer series 156's were definetly better built compared to the first series ('99 - '01).
Engine wise, JTS is probably one of the best engines in its class (when working properly) and thats manly due to direct fuel injection, which gives it more torque and a flatter power and torque delivery, making it easier for everyday driving (twin spark is a peaky little bugger

).
Make sure you go for a long test drive before you buy it and pay attention to a few things like:
-
motor oil level (some of JTS's like to drink oil like theres no tommorrow, although mine hasn't used a drop since I purchased it)
-
engine temperature - if after a long drive the engine temperature still doesn't wanna go higher than 70C when moving, it probably means that thermostat is busted (this is very common on all Alfa's)
-
engine seems lacking in power (it feels 'flat') now this can be caused by a few different things when it comes to a JTS engine. The most common one is a stuffed up MAF sensor (MAF is an air-flow sensor located above air filter box - what it does is basicaly sends an information to engine's ECU telling it how much air is passing through so that the ECU can adjust the fuel to air ratio in the engine)
It usually gets dirty over time (I think this is common with 156's because of the terrible design of the air intake which is streched all the way down to the ground- its almost like a vacum cleaner sucking all the crap beneath the car). The symptoms of this are usually feeling like the car has no top end- the power cuts out above 5000 revs or the idle is very bad.
There was also an issue with some early JTS's losing power because of the apparent bad design of the intake camshaft and bad ECU set up which caused some overlap in combustion process leading to carbon build up on the intake valves and thus loss of power (there is a big topic on this on
http://forum.alfa156.net/forum/forum_posts.asp?TID=37964&PN=1).
But apparently only some of the 156's built before the facelift in 2003 were affected by this, but it still might be a good read for you. Alfa never admited to this, but alot of the alfa specialists and mechanics agree that the problem was caused by the bad factory design.
Ignition coil packs (they sit on top of each spark plug and send electricity down the plug) also tend to die early for some reason- the symptoms are usually misfiring or stuttering when wanting to accelerate fast (this is usualy followed by 'Motor Control Failure' warning on the computer display- with the error code, which is retrieved at alfa dealership through their computer examiner, showing 'misfire on cylinder 1,2,3 or 4')
When it comes to
selespeed, you should be ok as the second series (post '02) selespeeds had revised actuator (electro-hydraulic device that actualy moves the clutch and gears) and selespeed pump (creates pressure with selespeed oil for that movement).
But it is very important that you take the car to alfa dealership to have the selespeed calibrated at least once a year (they do it through their computer - using actuator to adjust the clutch, take up points, check pump pressure, etc) and also check the selespeed fluid frequently (this is separate oil to actual gearbox oil) - it has to be on 'high' level to work properly, and only a specific alfa oil is used for it.
Selespeeds have gained a bad reputation in reliabilty becuasue most of the people tend to drive (and buy cheaply) the very first generation of 156's from 1999, when the selespeed system was just introduced for the first time, and a lot of previous owners never realy took care of them - never checking the fluid or calibrating them.
Also becuase the system is very complicated, people used to spend a lot of money on changing the entire actuator units ($3000 on average) where a simple electrical or wiring problem was the cause.
I think that the actual 5 speed gearbox underneath selespeed system (same box as regular manual) can cause more problems than the selespeed system because it has very weak synchros and bearings that don't like to take much abuse (try trashing the crap out of it for a few minutes and the gearbox starts sounding like bucket full of nails). So its also important to change the oil in the actual gearbox aswell.
When it comes to driving selespeed, you definitely have to get used to it, and remember - you cannot drive selespeed like a regular automatic gearbox cause its not. Its an actual standard 5 speed manual box with the clutch thats under control of ECU insted of your left leg, and you have to drive it that way.
I would avoid using the 'city' mode because in my opinion the selespeed ECU is not programmed well enough for different styles of driving and road situations. It has that annoying habit to hold on to first gear for ages, and then awkwardly jerk it to second (in the process making you look like a beginner manual driver

) and it also likes to quickly go through 3rd and 4th and then gets stuck in 5th, even though you might be going up hill or the revs are low.
Also if you are just crusing in 5th gear in lower revs and you suddenly want to accelerate hard, flooring the gas pedal will only result in dropping down one gear insted of two or even three that the regular 5sp auto would do.
The smoothest way to drive the selespeed is to drive it 'manual' mode and to slightly step of the gas everytime you change up the gear like you would when you drive regualr manual. This is when selespeed becomes fun to drive (even though the change from 1st to 2nd is stil too slow for my liking)
Outside the engine and gearbox, the only other thing you might look out for are worn discs on the brakes. For some reason Alfa 156's and 147's go through them like they're made of sugar as they get worn out realy fast even on low k's examples. Radiators also tend to develop leaks after 4-5 years due to low quality materials used in their build (I'm not sure if this is still the case with the last 156's made)
In your case you shouldn't wory too much because the Alfa is stil relatively new with low kays, but you should probably try and negotaiate the price further down as it does seem to be a bit steep (around $29000 should be closer market value). You will have to replace belts between 45-50k as they have a scary tendency to snap after 50k on JTS's - mine one did on 55k.
I'm sorry for a long write up, I didn't mean to scare you with any of these issues, I simply wanted to summarise every possible issue with this car in one easy to understand post. Alfa purchase is always made by heart, but I can assure you that if you are being smart it shouldn't cost your wallet too much