A few of us from Pennine did it last year for the first time and we really enjoyed it, especially the cosy pub afterwards. It's quite tough as you go up onto the ridge steeply and it then undulates to the summit over about 2 miles, so you've got about 4 miles of undulating terrain and it's remarkably easy to get disorientated - no big tracks here. The weather was cold, wet, windy and misty with big patches of sodden, deep snow last year.
You can read Alan's report here: http://www.penninefellrunners.co.uk/YrAran.htm
Hope you enjoy it!
Just noticed that you said you're in Snowdonia - be aware that it takes a long time to drive there cross country from Llanberis so give yourself plenty of time.
Richard