I've used CellCharge for the past year and have had absolutely no problems with it. The ten bucks is a low enough monthly fee for the convenience of taking cards (credit AND debit--very helpful since most folks, like myself, rarely carry a checkbook anymore). For clients who choose to pay this way I charge a $3 convenience fee per transaction, which covers my merchant and account fees. The vast majority of my clients pay with cash or checks, so I wanted something hassle-free and fairly inexpensive.
The funds have always been deposited very quickly, within the timeframe described. I've never had a problem with depositing.
I like that all I need is my phone, which I carry anyway. I note the transaction's authorization number on the client's chart (with all other info for that session) in case I need to reference it in the future, but I don't have to worry about carrying any other equipment or security and storage measures for receipts. The client's card information is not written down--you just punch it in as you go, and the ZIP code is right there on their intake form. Hand the card back, and you're done. It takes maybe 25 seconds.
If you WANT to do this the mechanical way where you imprint the card on slips, CellCharge can accommodate that, too. But that's not necessary for my practice.