I have now played the Mythos beta for a couple weeks and want to share some of my thoughts.
Graphics
The game looks good, albeit simple. The idea with simpler graphics is that it will be very easy for new monsters, races, and other art assets to be created for the game. Flagship Studios, Mythos' developer, wants to be able to easily add content on the fly.
Animations are all very well done. The game runs well on my gaming desktop and on my work laptop, so the system requirements are not steep. This is a clear benefit for the game as many different levels of computers will be able to run it.
Game Play
Game play, like the graphics, is simple. Generally, players set one ability to the right mouse button and their base attack to the left. From there it is straight up hack and slash. Players plow through tons of monsters at a fairly quick pace.
My concern for the way the game plays is that the character advancement is far too slow. It takes a good bit of hacking and slashing to advance a level. Gaining a level is the only time at which you receive points to spend on new abilities. Even then, the low level tiers of the skill trees offer very few new skills. It is quite easy for a player to get quickly bored.
Mythos needs faster advancement or a system that gives new skills on a faster basis. The game is supposedly going to be free-to-play, so there is no reason that leveling needs to be arbitrarily hard or "grindy". Currently it is very grinding intensive, with little flair. Grinding isn't particularly bad in a hack and slash game, but combined with slow character progression, it makes Mythos quite boring.
On top of this, the classes just aren't balanced. Some classes receive early access to area of effect (AOE) attacks that just dominate. Classes without AOE are at a significant disadvantage as they are forced to kill monsters one at a time, burning through a ton of potions in the process. There is plans to introduce more classes to the game, but I sincerely hope Flagship spends some time balancing AOE vs. single target attacks.
Just a quick note on potions. I absolutely hate potion mechanics in most hack and slash games. Mythos, like most games of its ilk, have players quaffing potions every ten seconds. This has never made any sense to me. Why not just increase the amount of damage a character can take, or mana a character has, and save some work for the database hardware?
Loot
A hack and slash game is nothing without it's loot. Mythos operates on a random loot mechanic. Magic items drop or can be found with random stat modifiers attached to them. At any time, a fairly powerful magical item could drop. However, I have some problems with the system.
The system is a fairly standard random loot system prone to the same old problems. Most of the items that drop are worthless, as they combine stat bonuses that are worthless to a class. Plus, a lot of items drop that are not even useable by your class or stat build. I am a little disappointed that Flagship made absolutely no attempt at improving the aging mechanic. They could of made the system more intelligent, dropping loot that is more optimized for your class or build.
Fortunately, Mythos alleviates these problems a little bit with a socket mechanic for plain items. Players can purchase weapons and armors that have sockets into which they can set gemstones that give various stat bonuses. This allows for players to achieve some sense of control over what stats their items will have.
Another problem I have with the loot is that it is not very easy to compare two items. Mythos would benefit greatly if you were able to display the statistics of two items side by side. Also, a "Is this better than what I am currently using?", suggestion box would help new players immensely.
Conclusion
In the end, Mythos will be a fun game to mess around with when players are bored with their main game. Mythos is also a great casual title. Both because it is free and because its game play is rather simple. My only concern is that they will not speed the character progression up, resulting in a bunch of bored players. With a bit of polish and flair, Mythos will be a new age Diablo (minus the demons).