It is - just need to make sure you validate your pass at the JR office in the railway station at NRT.

If the HND flight had the same (or better) timings than the NRT flight then it would be attractive. Personally I would find the LHR-HND flight too early an arrival for my liking, and the return flight time is brutal IMHO.

I flew out of the HND International Terminal on JL last Sunday (on a very civilised mid-afternoon flight to GMP). The terminal is very compact (a welcome change from NRT!) and it was nice to be able to get a cab (25 minutes from my hotel) for JPY6,000, which is not much more than the NRT Express costs.

NRT can sometimes be an easier (if not quicker) option than HND though. My firm's offices are next to Tokyo station, and from there the NEX is 53 minutes to NRT T2 - not bad really.

In terms of lounges, the main ones belong of course to JL and NH. The JL lounges are both in the same place, close to Gate 112 (turn left after immigration). The entrance is on the same level as the gate area. When you enter, the First lounge is to the left and the Sakura (Business) lounge to the right. The First lounge had a lovely view across the apron towards the domestic terminals and Tokyo Bay, and some really nice recliner seats in private booths by the windows - very private. Food is just about OK (nice sushi and a few reasonable Japanese options, plus pastries, muffins, etc, and nibbles. Drink consists of Suntory Premium Malts Lager on tap (complete with chilled glasses and a beer machine to pour the perfect glass), mid range spirits, basic champagne (not a brand I had heard of) and a choice of two 2010 reds (one Chilean, one Australian) and one 2009 white (Chardonnay from NZ). Good range of English language papers on offer.