Make sure you sign no agreements barring you from trading elsewhere if you don't like it where you are and decide to quit (non-compete clauses).
.005 isn't great, but it depends on your volume. If you do over 100k shares a day, or 2 mil a month, then you can get much lower (I got .003 after shopping around). If you do 25k a day, then .005 is fine.
Check to see if they charge you other fees beyond the desk fee. Data fees, open book (if you trade NYSE), software fee. Sometimes firms that charge lower rates make up the difference in these back end charges.