* It seems to require at least 4 players before a match will start, and can fit as many as 8 people. (it seens for me too)
* The entry cost is 200 crowns per player, and the winner is the only person who gets a payout (in 4-player mode, at least)(it appears to be the same for more too)
* When 4 people compete (total entry cost = 800 crowns), the winner gets 560 crowns. This suggests that 240 crowns (30%) disappear from the game permanently: the coliseum is a crown sink.(yup)
* Every player can run just as fast as you, and there are a lot of wide open areas. As a result, bombs are really easy to dodge, and swords are much harder to use than you'd expect. ("Come back here so I can poke you!") Since you're only going to get in one hit, the slowness of the khorovod isn't an issue.(i will comment this latter, but you're wrong in some parts)
* The vial and heart respawn areas are cool, but their position at the edges of the board (protected by spikes) encourages some people to camp out there and snipe from the edges. Putting item spawns in the center of the board (exposed to attack from all sides) would make them less abuseable.(will be commented too)
* Armor costumes are ignored in the arena, so you always know what your opponent is actually wearing.(didn't knew that, so, it is good ^^)
my add:
* When a player dies, it will lose points, and when a player kills another, that player gets points at a rate similar to the lost points from the other player, making so that the player with mst points to be targeted more easilly. Also, at tier 3 (the only one that i tested), there are cages that respawn, and, when broken, let out a random moving monster (no gun puppies), tha can be a problem to some players. It is interesting, as you need to be aware of the others players AND the monsters spawned.

About meleeing and ranging in safespots: well, the coliseum is really more based in movment and meleeing than most things. You can make a real use of bombs and melee in there. For example, if you see someone with a weapon with high knockback (like khorovod), them you can put a bomb where the person will ladno, and, if well times, will make so you steal the dead from the other player ^^. Also, ranging is good for extra damage and status effects, but not ass main damagers, becasue of low damage rates. Standing in a place ranging in a "safespot" is suicidal, because the player can simply go to you and hack you with some slashes. A well timed khoro hit can mostly kill, or make it real close to this (tested myself: meleeing is good, don't matter the melee weapon, as it stops other players actions in the last hit, and if timed so that the second hit only lands, can make quite a mess in the target's health).
I liked it mostly because the fast pacing battle, the good balance, and the fact that if you're standing still in a place, then you're dead meat if someone notices you. i myself tends to iggnore the one running to me with a khoro to kill a pest with a ranged weapon then to turn back in time for fighting the one pursuing me ,if he didn't stopped the pursue to pursue the one shoting too.