What you make of it scousehiller. if you go in with a keen can do attitude you'll be enabled to succeed, especially with the resources in HMS Eaglet (Your local unit).
Go in with a negative outlook and you'll probably leave with one.
The RNR can provide you with some opportunities you and those you know, will never get to experience elsewhere. You'll get paid to do AT or at the very least heavily discounted for long courses. There's also an active social element. Oh and an annual bonus (bounty) tax free.
Downsides- Pay/entry into service can be a slow process sometimes not, you have to do a lot of classroom based activities before you can do the more exciting things (train into basic role).
I'm sure others will add to the list however it's best to remember that whilst this is a fantastic opportunity and can lead to a lot of amazing things it is a paid job and therefore subject to the same administrative headaches you'll have anywhere.
You do get to decide when you work, bar vital events e.g. rememberence day, yearly review (Co's divisions) etc. And that flexibility is excellent.
Give it a go, come back and tell us what your impressions were? It's always good to get fresh perspectives.