If you want something different, this is great. We had a 4 course lunch & coffee and paid £18.50 including the cruise - which I think was good value for a menu which included steak.
Whilst the whole thing is slightly ridiculous (you don't go that far) and I've seen better views from canal boats (e.g. you're not going over the Pontcysyllte Aqueduct) the crew are great and make it a fun occasion.
Would I recommend it? Well I rarely go back anywhere - but I've done this twice!