I have to disagree slightly, i work in a dealership right now, and yes bad things are said constantly about them but its not always the case. In my 1.5 years at my workplace now iv had the chance to work on a range of models, citroen, alfa romeo, fiat, lotus, mg / rover and random trade ins that you get so there can be a bit of diversity. Everything is about who you work with, obviously you cant choose them but if your with a great team it makes for excellent working conditions.
some of the mechanics i work with are the best blokes going around and have just taken the time to teach me so much, iv also been lucky enough to tackle big jobs by myself to learn faster and the support is there if i need it. The cars i work on are very electronic controlled so there is always plenty of diag to learn. It's rather funny to see the apprentice know the ins and out of the daig computer program when a qualified mechanic doesn't even know how to hook it up to talk to the car those are the people who are only good for putting a part on.
but yes long term it may not be the best career choice, but its always worth a shot