I have used Ionomy for years. The problem with it is that liquidity is poor. Difference between a lowest price you can buy something for and the highest price you can sell the same thing for, is often very wide.
Take the ION/BTC token pair. This is kind of a focal point for this exchange. It is the default token when you open up the trading view and it sounds like the name. I speculate that is where the name comes from. Measuring the difference can be superficial, if you can only trade one cent at the best prices in the order book there is no practical value in this. Suppose you want to buy something $20 seems like a good amount to talk about. For others it might be some other amount, but lets go with this. If you have Ions, you can sell them at 18 sats/Ion and you can sell up to 641 Ions. If you fill that bid, that's about $2.31 (115µBTC) worth. The next bid is 8 sats/Ion. You then need to sell 11062 Ions to get $20. So now at the $20 depth the sell price is 8 sats/Ion.
Over on the buy side, it's 39 sats/Ion to buy only 427 Ions. This is so much higher than even the lowest depth sell price of 18 sats/Ion. In order to put $20 worth of BTC you would end up paying 59 sats for part of it.
Doge is a very popular altcoin. So looking at the lowest buy price and the highest sell price at a $20 depth, there is an ask price (the price you buy at) of 320 sats/DOGE and a bid price (the price you sell at) of 313 sats/DOGE. The depth of these is around 4mBTC ($80). That's only a 2% difference. This exchange is useful for this pair.
Sadly, HBD is even less popular than Ions and the liquidity of this exchange is even worse for this pair than that of Ions vs. BTC. Your best sell price for HBD into BTC (@$20 depth) is 26.2 µBTC/HBD. This is like buying BTC at $38,200/BTC-- a really bad deal. The lowest ask is 99.68 µBTC/HBD. This is comparable to selling your BTC for $10,100 each! Just horrible.
If you buy these without working out whether it is worth the price you're paying, you're a fool. In some circumstances the rates can be good. You have to take into account how much you're trading, and what the prices will be at those amounts. Also there is a withdrawal fee on top of a trading fee at Ionomy.
A liquidity provider can put too deposits for HBD and say BUSD. Put the prices relatively close together with in 2% of each other. I did this for HBD and BUSD pair over here. The best buy and sell prices were 0.251 BUSD/HBD (!!) and 1.40 BUSD/HBD respectively before I put my orders in! It took a very long time before a buyer came and bought my HBD and then a long time before someone sold me back HBD. If people traded with me over there more often I could add more but the exchange itself isn't known by many thus the poor volume and terrible liquidity.
For the purposes of this article I'm taking the exchange rate to be 1 BTC for $20,000.
