Hi Rosco,
welcome to the forum.
The expat scene here is quite lively, but they do tend to be mostly in their mid-twenties upwards. Nevertheless you will still find plenty of people in their early twenties.
Plenty to do in Munich and the clubbing scene is quite a busy one, including the wannabe-snobby clubs which are so fussy they reject most people turning up.
The best features about Munich are:
- transport - second to none
- crime levels - very low, even for Germany which is generally a relatively safe place
- high standard of living - the pay here is good and the environment backs that up
- near the Alps
- good night life and cafe/bar culture
- major city with a small city feel. As Laneris said, many districts have a small town feel
The not-so-great side
- Low crime means less need for politeness among the Müncheners
- People tend not to move properties frequently once living here, so deposit and estate agent fees are high. Often moving into a place you will find everything gone, including the light bulbs and kitchen.. yes, I mean the entire kitchen can be completely empty

- Police are very efficient... don't even think of crossing the lights when they are not green, or even saying something opffensive to them. Not using the polite form of you, i.e. Sie is an offence and can have you fined!
- High standard of living makes Munich the most expensive city in Germany
- Weather... far better than anywhere in the British Isles, but still not as good as you might like
- Laws - German laws are a double-edged sword. Try not to speak too loudly in your flat outside the legally permitted hours, else you might get a nice little visit from the Polizei. Don't even think about playing loud music past 10pm.
Overall, it is a great city to live in and you will find it very relaxing and enjoyable, especially English Garden in the summer. Just obey the laws and don't sign anything unless you have really read the contract thoroughly. Companies here will often try to trick you with false claims and offer you a different contract to what they said they were offering - consumer protection here is light years behind the UK. Sad, but it happens all too often, especially to expats who don't know the culture here.
If you need help settling in, then give
SIMunich a shout. Very cheap service, friendly and they can help you through the minefield of bureaucratic nonsense which you need to follow, i.e. for registering a bank account, registering as living in the city, acquiring a mobile phone, getting personal liability insurance (very recommended as people do sue here if you damage their property in any way).
Also, ask away here and get the answers to your questions. That is why we are all here.