I've taken Silverjet four times now, and have sat both front and back. Your best bet is for seats in Row 9, as they have oodles of legroom. Ask at check-in if they are available. Otherwise, I'd plump for the back. The seats seem to have about 2 extra inches of legroom, but other pax are so keen to sit forward, you invariably have the seat next to you free. Avoid the last row as there is a galley right at the very back which could be noisy. Service wise, I seem to have pretty quick service in the back, too. On return flights I've had 2B once, and that was fine, but service seemed a bit slower.
Do check out the menu online. If you don't care for any of those dishes, you can select from about 30 other dishes. I've tried a few for variation, and they are all good. If they still have the cod outbound, give it a try - one of the nicest dishes I've had on a plane! One other tip, have a bit of breakfast in the Luton lounge (they have pastries, cereal, fruit). You take off at 10:00, and they don't do any service before midday, which is fine, but for those who haven't had breakfast thinking you are going to have something as soon as you take off, those two hours can be an awfully long wait. Nice canapes with drinkies at midday, followed by a four course lunch. Wines are so-so, the could be better. Nice to have personal service - no carts in the aisles. Afternoon tea is just a mug of tea and a slice of cake (last trip was apple flan). Since they start lunch at midday, it makes sense to have a lighter tea rather than the full works, which would be too much.
Amenity wise, they now have a trolley of newspapers once you board (but there are plenty in the lounge), and toothbrush/paste has been added to the socks/eyeshade pack. Nice toiletries in the lavs, too.
Have a good trip...I am enjoying using them. I certainly don't miss the airport hassles of LHR for sure! Silverjet has been easy, easy, easy so far, and a huge cost saving over legacy carriers.