Do you download for on the go much Mantis, or just access online? I'd probably mostly use it while I'm at home. My daily commute is only 30 mins, so that's not a big deal. I usually read sports news or play Warhammer Quest.
I mostly read at home, but I have used the offline reading a few times without any problems. You can save up to 6 comics for offline reading at a time so if you only need to fill 30 or an hour you should be good. Next time you have service you can switch them out and save up to 6 more, etc.
My biggest annoyance with the service is that some runs on titles will be missing one book in the middle of it, which drives me crazy, but I've only seen that a few times so far. I used to (before the wife and kids) drop 70 bucks or so a week on comics, so this service is a deal and has allowed me to fill in the gaps since I stopped buying. Also, buying that many books I was starting to have to think about doing something with all that paper, with this I I don't have to worry about becoming a hoarder. I plan on renewing in July when my sub runs out.
Games
How to resolve AdBlock issue? 
