*Anti-tank weapons will destroy your tanks in short order.
**Now stop and think about those above three points. Together, they constitute a major challenge when faced in tandem. Enemies can reap bounteous rewards through good target selection against the IG, and it can be tricky to find ways to deny their efforts. Take a typical mixed-unit army, some infantry and some tanks. There will be times when the enemy can pull off a highly effective attack, pointing their dakka at your infantry and their blasta at your tanks. Some units may have to be sacrificed to an effective enemy - let's say a unit of Sentinels against enemy melta fire - if it means guarding a more important yet similarly vulnerable target - your Leman Russes - until you can wheel a more effective counter unit into place - disposable infantry squads. You can only anticipate so much! The standard wisdom when designing an army is to aim for a uniform defensive approach between units, to prevent easy target practice for the enemy. But the IG are very dependent on synergy, so taking an all-infantry or all tank army is also quite risky! Whether it's a mixed army that demands carefully positioning and tough sacrifices, all-infantry that runs the risk of weak output or all-tank brigades that struggle to shoot fast enough, you've always got a catch when constructing your wall of shooty death.
*Playing Imperial Guard can be tedious. Whether its literally counting out ''hundreds'' of dice for shooting (bring bags, and expect to lose some) or spending more than half an hour just deploying your army (movement trays, learn to love them). Fortunately your turns will go by faster once you start piling up casualties.
*Although your units are cheap in points, they're not that cheap in cash, ''particularly'' if you buy from Games Workshop, instead of a cheaper source; four maxed out conscript blobs will run you $160, not to mention the difficulty of painting and hauling around 120 3 point bodies, and that's far from the most expensive option. You ''will'' want to find a cheaper, alternative source of models, unless you're interested in supporting your FLGS - store owners ''love'' new Guard players.
*You're not GW's [[Space Marines|favorite children]], so not only are new models for your army very rare, but your infantry models are mostly outdated as fuck and are rarely in stock.