I have a 1200 GS and bought my wife a 650 CS when she passed her test, mainly because it was the only decent sized bike my short arse wife could get her feet down on. I still had to wind down the preload and move the forks up the yokes so she could drive it.
My wife did her training and test on a 650 GS AT BMW Rider Training and to start with she did not like the slightly sporty riding position so we fitted bar risers and now she loves it.
The CS has never caught on in UK but its a great bike although the styling is a little strange. When I first rode it, it felt like a moped after the GS but keep it revving and its a real fun bike. A friend with an R6 tried it and I thought he would be really critical but he came back with a big grin on his face, telling me how much fun it was on the twisties.
No chain, its a maintenence free belt drive, my wife likes the stange cubby hole in the dummy tank becuase its great for shopping, rucksac and somewhere to lock up a helmet. Fuel consumption is pretty good and the headlight is suprisingly, for a bike, efficient. As they have never caught on, the prices are good, for BMW, as well. Our immaculate 2003 bike with 13000 miles on clock cost £2600 - and it was cheap to insure. We were amazed to find BMW Insurance only wanted £110 to ensure a brand new driver.
Downsides. The finish on the Rotax engine casing peels off. This seems a problem on every bike we have seen. It's difficult to get panniers but BMW have a really clever soft top bag system which expands over the pillion seat. After getting used to BMW switchgear I HATE the Jap type indicator switches that are fitted on all the BMW 650s.
Overall I think its a great first bike.
But then is the 650 really a BMW?? It has a chain and a Rotax engine, sort of sad that a company that started making aircraft engines in WWI and made great thumpers all throughout the 30s 40s and 50s can't make their own singles anymore. 
