The Deadmines is a midsize instance. It took my group about 15 minutes to complete it. There are a few things to watch for during the instance itself. Burnt places on the ground (one at beginning & many on the dock) indicate an area where canons are being fired. Avoid standing on these and time running across between cannon shots. Another general note is about trash. Some trash will cause the drunk effect onscreen. It only lasts a few seconds.
Deadmines has a few higher mobility demanding bosses but most mechanics can be handled if you move early and often. It isn’t overly long and has no jumps although the ship does have multiple ramps winding back and forth to top deck. If you’re hand or arms are easily fatigued by stairs ingame, be prepared. They are contained to one specific area.
Specific Boss notes available at http://abilitypowered.com/blog/?p=153 for anyone with hearing impairments.