Stayed at the Arts last year in August and was mightily impressed. We had a deluxe double and didn't have lounge access so can't comment on that. The location means that a 15 - 20 minute walk into the centre is required but the area around the beach and Olympic Port is really trendy.
The conceirge was very helpful with restaurant recommendations and reservations.
Would definately stay there again, but on a high floor with a sea view!
Hope that helps.