It can be tough trying to choose apps from the iTunes App store for your iPhone/iPad Touch/iPad, especially if there's no "lite" version to try out major features first. At that point, you've got to rely on reviews, which can be all over the place.
Take Desktop Connect for iPad for example. It sounds great – a remote control program for both Macs and Windows. If you read the reviews, for some it's working great. But today, the majority are giving it 1 star. That wasn't true when I bought it – there was a slight majority of 4 and 5 stars. So I took a flyer for $7.99. Guess what? It works for me like it does for the other 1 star reviewers – it's awful. It's incredibly slow to repaint the screen if it connects at all – which is very odd, because it finds all my Macs very quickly. In its current state, it's useless to me. But to at least some folks, it's working fine.
I spent a lot more time pouring over reviews after getting burned (although, "burned" might turn out to be harsh – the software may get fixed at any moment, since many people are rating it poorly). I decided to give another app a try – iTap RDP client at $11.99 ( I need RDP for controlling Windows machines at work). This app also has some negative reviews, but not as many as the positives. And for me, it works great! So I also sprang for iTap VNC client to control my Macs (on sale as of this writing for $7.99). While neither of these programs had the great auto-discovery feature of Desktop Connect, they do actually connect to my systems, and are very fast. They have some unique gestures you need to learn, but they're not that tough, and they also have a "magnifying glass" feature that lets you really zoom in on something without zooming the whole screen. Of course, you can do that too if you want. It also has a special mini keyboard (in addition to the regular one) that has arrow keys, function keys, and the like.
So sure, it cost me over twice as much, and I now have two programs (so I can't switch back and forth between Macs and Windows machines at the same time, which would be nice in a few circumstances). But at least these programs work for me, and they also work on the iPhone (although I really can't see myself trying to do much remotely on such a small screen). Maybe at some point Desktop Connect will work too – in which case I'll have options in case one works and another doesn't (I like backup plans).