Mandatory premise: even though I stuck with the game long enough to obtain all achievements (and boy, some of them were a painful grind) and I really wanted to like its frantic approach to the tower defense genre, I can't recommend it to anyone for 5 bucks. You may find it interesting if you paid a maximum of .99 cents or found it as part of a bundle, but other than that there are way better TDs on Steam for its base price (Fieldrunners, iBomber Defense and Alien Hallway, just to name a few).
First of all, the pros: game is weird. Like, REALLY weird. Your objective in each stage is protecting the main tower of your hotel by building square shaped rooms around it. Rooms come in three distinct flavors: defensive, which simply stand there and absorb hits until their eventual annihilation; offensive, which provide the classic fare of TD weapons (guns, mines, ice to slow enemies, etc.); healing, which do exactly as their name says, replenishing damaged towers (but not themselves).
Rooms cost money, obviously, provided by the main tower at a really slow rate. To make your income skyrocket, you must build defensive rooms which also generate revenue, so you should maintain a balance between defensive and offensive ones to obliterate enemies, expand your layout and replace those destroyed. There's also a bare minimum of architecture in play, so if you stockpile rooms and enemies manage to destroy a block in the middle, all the ones above will crumble. Rooms also resonate between themselves, so you'll also hear a weird (again) but enticing tune while watching 'em shoot, heal or gather money.
Enemies, which range from giant bees to angry clouds through swimmers, snakes and pigeons, come at you in waves. You have a small interval between each wave to plan your layout, but actually the pace is so wild that you'll end up improvising most of the time.
And now, the cons: first of all, Bad Hotel is a port from mobile. While not necessarily a deal breaker per se, leaving controls unaltered really is: you must drag each tower on the map from the bottom bar, without keyboard shortcuts of any sort, and this alone would be enough to make most players back off in disgust.
Moreover, the taller your tower, the farther the camera will be placed, and you'll end up with a tiny tower being chipped away by tinier enemies with greater chances of screwing up room positioning due to the shrinked (and un-zoomable) visuals.
Your rooms selection is also limited in each stage, which in turn severely restricts your strategic options, and levels are intense but few and short. Finally, bosses are the nadir of stage design, since you'll be practically forced to go all out on them before being overwhelmed by waves of normal enemies.
As I said in the beginning, I had fun somewhat with this game while it lasted, but for all its quirkiness I feel it's also brought down by its many shortcomings, and thus cannot possibly praise it as much as I wanted.