Thinking of getting one and could do with some opinions.

4 British sailors in the top 10 at the worlds in San Francisco at the moment but Ben Anslie will still get the nod for the 2012 Olympics! There is a good Masters circuit so I'm told.

Haven't sailed one myself, but years ago in my sailing days a couple of mates tried them. IIRC the verdict was very, very hard work, very complex (takes forever to work out how to tune them), and very expensive. Also, you have to be quite big, very fit, and able to carry a big weight jacket. Apart from that, would you find anyone else to race against locally?

I always fancied a Contender but never got around to it

Olympic classes are always expensive to compete in. For the performance they cost loads. Check out the rs100 and the devoti one for a new take on the design.

How heavy are you – think the starting weight for finns is something like 15st.

Consider alternatives such as Laser, contender, rs300, musto skiff (my choice), rs700, devoti one

They have a complex mast bend, sail shape thing going on that may create problems when buying second hand equipment.

Olympic classes are always expensive to compete in.
…
Consider alternatives such as Laser

So a Laser isn't expensive to compete in?

Olympic classes are always expensive to compete in. For the performance they cost loads. Check out the rs100 and the devoti one for a new take on the design.

A mate has an RS100 which I've sailed a few times, nice but I think has its issues, one of which is that they are proving 'interesting' to right after a capsize (hull floats pretty high due to the wings so quite a lot of windage and likes to capsize on top of you when you try to climb back in)

How heavy are you – think the starting weight for finns is something like 15st.

I'm 90kg (14st) right now – I used to think that I was too small for one but it seems that the starting weight is now about 80kg. This was never the case (hence the, now banned, weight jackets) but the advent of carbon rigs allows a sailer to get a mast that has the right bend characteristics for his weight/age so more people can sail them. Mr Ainsley was about 85kg in the last olympics.
I've chatted with a few people (including a past Masters World Champion who lives about 4 miles from me) and, although on the lighter side, I'm in the right area if I can get the right mast.

Consider alternatives such as Laser, contender, rs300, musto skiff (my choice), rs700, devoti one

Got a Laser now and a bit bored with it. Had an RS 600 for 3 years and then a Musto for 2 years but never could give it the time it/I needed plus I probably live in the wrong part of the country. My initial thought was to get a Contender but the Finn does a lot better on handicap and I think looks a nicer boat.

Apart from that, would you find anyone else to race against locally?

I live about 30 mins from West Kirby where they are expecting 4 or 5 boats training over the winter and I could also do mid-week evening racing there come next spring.
An additional incentive is that the Finn Masters Worlds are being held in Pwllheli (N Wales) in 2012 and my Mum has a house in Abersoch 10 mins away where we spend the summer hols.

The whole thing would give me the chance to sail through the winter against some very good sailors which could only do good things for my racing.

Edit:

They have a complex mast bend, sail shape thing going on that may create problems when buying second hand equipment.

Yep, it's important to get the right rig for your weight/age otherwise you'll be well overpowered in anything above 12knts. Luckily each mast has a certificate that says what that masts deflection numbers are at 25%, 50%, 75% and 100% mast length when a 12kg weight is suspended from the tip.
I've found a boat with the right numbers 🙂

With regards to cost…. they are expensive to buy but I could spend £5000 on a used boat today and probably still get £4000 for it in 3 years time (if they stay an Olympic class), or I could get an RS100 for £7000 now and sell it for £4000 in 3 years time 😐