I'm so relieved Nintendo is going back to cartridges becasue having to install games always seemed like a step backwards to me. Faster load times, durability, and ease of use are a huge plus if this is going to be a consumer friendly device.
The Switch will literally the most powerful handheld ever that happens to play games on a tv. I think it's touch screen will allow for a great mobile experience while the joy-cons/pro controller will allow for a great console experience. The best of both worlds. The novelty of having an all encompassing gaming device that can play mobile games, Nintendo games, and 3rd party games is very appealing for casuals and core gamers.
And for those worrying about power I think Nintendo is adopting the Apple model. On paper the specs may now blow you away, but becasue everything is optimized and custom specifically for the platform the games will still look great. Plus I'm sure later down the line Nintendo has plans to release docks with added power or different tablets with more power at very reasonable prices keeping pretty much the same Eco-system in tact.
After all, it's rumored to only be $250. I highly doubt the base Switch model will be more than $299. That is insane, unless it has extra power and functionality we don't know about.
This thing is going to be big.... Get your pre-orders ready!