It’s a hard one. Plenty of people here would happily spend £80 just on the tires.
Assuming everything works okay, it still seems a little overpriced to me.
If you need to start replacing bits, the price can quickly rocket too. An example being, if you need a new chain and new cassette (the gears at the back), new gear cables and outers (the black tubes the cables pass through), it could cost another £80.
It is worth remembering that if things break, it can end up being very uneconomical. The cheapest 26″ ‘road tires’ I can find are £10 each. 25% of the cost of the bike!
Take it for a ride.
Do the brakes work?
Do the gears shift properly?
Do the wheels spin freely (listen for grinding sounds in the hubs) and are they true?
Does the handlebar rotate smoothly?
From the sound of it, you don’t even know if you’ll enjoy riding. It sounds like it could be a good bike (Specialized are nice bikes, in general) for you.
From the ‘replace it with road tires’, I guess the riding will be on road. I know these are in Brighton but, for joining the missus on 10 mile rides, I’d be looking at bikes more like these.
http://www.gumtree.com/p/for-sale/raleigh-531-eluxe-2nd-hand-racer/1075745222
http://www.gumtree.com/p/for-sale/universal-hybrid-bike/1078782166
http://www.gumtree.com/p/for-sale/mans-23-inch-vintage-racer/1078747863
Even if not, your friend seems a little (but not massively) optimistic. Photos of the bike might show some upgrades that justify the price…
Happy riding