Coldcurse, Simple: as the game initially requires a login separate from steam, you would use that to log in to your Guns of Icarus account, and play from there; also, the wifi connection would be as bad/good as it would be on a PC, sometimes better, as tablets (such as that new iPad) can sometimes have better connectivity receivers utilizing protocols such as 802.11n or 802.11ac, which some computers used these days still don't have, (or the routers) also, with the rise of 4G networks, connectivity on a phone/phablet/tablet with data plan is speedy, with an average of 3 megabits per second downstream, 1.5-ish megabits upstream amongst cellular carriers. This is faster than the typical broadband network, so connectivity is not an issue.
Gilder, there could even be some perks to using a tablet, such as reduced response time, as signals do not need to travel through blootooth/cables from a peripheral device (i.e a keyboard/mouse) to reach the processor, thus lowering response time.
Anyways, we'd need a way to move around: I suggest an on-screen direction pad (similar to the type used in Minecraft: pocket edition) and voice commands shouldn't be needed, as almost all popular tablet models have built in microphones (usually bundled with a camera) and if that fails, maybe sliding with 3 fingers would bring up an option on the side to choose which channel to use for text chat, which could bring up an onscreen keyboard to type with.