I've taken this flight (TLV-LTN) a few times, and it's been nothing like the low-cost airlines. It's the regular ELAL service, food, 'entertainment' etc. Admittedly, the planes are not the 74's or 77's, but all times that I've flown it, we've had newly refurbished 76's.
It's very good for getting in to London early in the day. Only downside, of course, is that it's Luton

One tip - if you have someone coming to pick you up, get them to stand off at the hotels just down the road - then, once you've landed and gotten your luggage, give them a call to have them swing in and pick you up. Reason for this is the the car park is horrendous, and expensive...
Alternatively, the number 757 bus goes straight to North-West London (Brent Cross), and costs £14 one way/£15 return (the return is valid to be used within 7 days)