I fished there from the bank last weekend, the fish were nailed to the bed of the lake and pretty sulky, it was an extreme weather day and I only lasted a few hours due to some very heavy rain driven by a strong southerly gale.
Llys y Fran is still well stocked and I left with three good fish. Like dave p I fished a black and green booby - green fritz body, black eyes - but on a Di7. On a warmer, calmer day lures, especially bead eyed, orange microfritz bodied, orange marabou tailed ones work really well on an intermediate. If there's any sign of surface activity switch to nymph fishing and a floating line. A team of diawl bachs with a 2 mm red tungsten bead headed one on the point can be good fun. I generally use 4 or 6 lb Maxima and haven't been snapped off for a few seasons.
The fish are a good average size, all mine weighed over 2lbs last week. They have a well earned reputatation for eating well, fighting power and their exchange value in local pubs.
Due to its elevated and exposed location a day afloat on Llys Y Fran requires a reliable set of waterproofs and warm clothes - add 15mph to the general wind forecast and you're generally about there. I completely blew it last week as what I took for chest waders in the boot turned out to be thigh waders which, in the circumstances, led to a bone chilling afternoon, try to avoid that basic kind of cock up and be prepared.
Good spots - the boat house is just above the dam to the east. The point almost due west of the boat house (bird point?) is a snaggy shallow area and always holds fish, look out for fry feeders. Fishing close in to the far west bank to the west of this point into the bay is also a very good bet.
Most boats leave the boat house, turn to the north and fish the shallows at the end of the long arm following the east bank all the way. It can get crowded but on the whole this is the safest bet for a series of long drifts and at this time of year it is relatively quiet. Having said all that the bank fishing is really excellent and much more enjoyable than a boat IMHO. Tight lines whichever way you approach it.