These days brokers all have apps which enable trading from a smartphone. I think it's a bad idea to trade from a phone just because of the clumsy mechanics of opening and closing trades from a phone. If you must execute orders while you're away from your PC, I suggest using a stylus pen, so you won't screw up the order entry.
I think it is totally worth it to sometimes trade on your phone. There are high chances that there could be some kind of problems with your computer and then the mobile is only thing that comes for help. I believe it is wonderful to use your mobile for all your requirements.
I've never done it... When I make a transaction I prefer to do it properly on a pc. I think it's safer and faster that way.
I have a very simple phone therefore that it is not an option for me. That said I prefer trading from a laptop because it is mobile and one can take it everywhere. With free Wi-Fi in most public places one is able to trade and make that extra coin even when far from home. I am saying this because I am not attached to a Smartphone. I am sure that my sis will have a different answer seeing that her phone is part of her ensemble.
Safest bet would be trading for a pc. Mobile phones are pretty risky nowadays especially if you have it infected.
As much as i love my phone, i'd rather use it to listen to music or browse, nothing serious, as for the serious stuff, the laptop comes in handy ...i feel safer using my laptop for such matters unlike the phone.