Firstly i would like to apologize for the lateness of my review, i have been having some issues with my internet as of late.
Pros of mixtum.io:
i felt the site was very clearly displayed out and easy to understand, nothing as jarring or offputting to the eye, and all the essential info is there and easy to access.
using the site itself was super easy as well, 3 clicks and your set to go, no hassle or anything of the sorts.
coins you send arrive on time within the 6 hour window they provide long with a letter of guarantee.
Cons/improvments for mixtum.io:
okay so, i think there is definitely room to improve, while the site is clear to understand, i feel it would benefit from a little clean up as well as making the hyperlinks to navigate more viewable.
Next, i was fairly disappointed that you do not currently support segwit/Bech32 addresses and fee it is something you should 100% work towards in the near future.
The fee for mixing i feel is a tad to high, but nothing in the realm of absurdity, however, this being my first time using a mixer i have no fees to compare to, as long as your fee stays competitive then thats alright by me.
lastly, while the site was vary easy to use, i was took back a little by the lack of control you have in the specifics of the mixing process, such as changing fee price in exchange for slower/faster delivery of the coins.
Overall i think your site delivers on what it promises. i sent coins, coins was mixed, i received coins. all in all i think you have a very solid foundation, now you just need to perfect the imperfections. good luck!