I have to agree that the mouthpiece is a little big. I see what they were trying to do with making a tip you could clench in your teeth and vape hands-free, but I find the battery a bit heavy to do that comfortably, so I just don't use it in that way.
Another thing that would be nice is to be able to just buy the smileo body on its own separately from the cap. It seems a bit wasteful to toss out the cap when it's just the body of the smileo that's dead. The caps would likely last through many more uses.
But, all in all, I'm really liking the Zeus system. I was looking at all the various VV/VW mods out there but they're just so big and cumbersome. I liked the size of my eGo Twists, but they have their own issues. The performance drops off over time. I have to have several since I can't vape and charge at the same time. I often had to pull the posts a bit to get them to fire with some of the 510 clearos I used, or even use a 510-to-510 adapter (which I keep misplacing).
I had been thinking it was time to upgrade my kit. I didn't think I'd be interested in something non-variable, but the system as a whole just works. The 5v battery is just right for the resistance of the smileo. No tinkering. Plus it looks awesome. I do care about that. I've been through so many different clearos and tanks trying to find something that gave me a clean flavor. It's pretty refreshing to just be able to throw some juice in this thing, screw it on, and know I'm going to get an excellent vape start to finish.