I own both and am thinking about returning the iPad (I made a thread about it) since it's important to me to have a smartphone. I do feel there is quite a bit of overlap (which is why I'm thinking about the iPad -- it's hard to decide when to use the iPad over the Evo or a laptop, or which platform to buy an app on).
Anyway, here are my thoughts.
- Both are great products. I haven't had any quality issues with the Evo and it feels very well polished. Android runs extremely well on it.
- Apps are more expensive on the iPad and there's no trial period, however there are more professionally done apps. There's more creative apps on the iPad by far (drawing, photo manipulation, music sheets, and so on). Android tends to be more geared towards productivity tools, "geek" apps (ftp clients, torrent clients, wifi sniffers, etc.), and free apps.
- I'd say that the iPad wins in gaming, except for two things: 1) iPad games are expensive (usually $6 - $12 for the good ones), and 2) the Evo can run NES/Genesis/Game Boy/SNES roms without jailbreaking and minimal cost (couple bucks per emulator). So it depends on what types of games you want to play -- old classics or new touch games.
- The Evo obviously has multitasking so you can do other things while playing Pandora, podcasts, etc.. It also makes the OS feel VERY fast as you can switch between apps without going back to the home screen (and loosing any work you've done in the process). Downside is that those will eat the battery up quick. The iPad will have multitasking in a few months, and if you are willing to jailbreak it you can enable multitasking now.
- Battery on the Evo is usually down to about 20% at the end of the day with moderate usage (half hour of calling, few dozen texts, half hour of web browsing, hour or two of other misc usage). Same amount of use on the iPad and I'll have 80% of the battery remaining.
- eReading / news reading / etc. is better on the iPad, unless you want to do some quick reading while in a checkout line or something. RSS is still very good on the Evo, which I use it a lot for (NewsRob is an awesome app). One downside to the iPad is the screen resolution. It's around 130 PPI or something, so there is noticeable text fuzziness, whereas text on the Evo (and especially dedicated readers like the Kindle) is much sharper.
- Web is not bad at all on the Evo. The screen is plenty big to fit a good amount of text on screen, and zooming in causes the text to re-render so it fits on screen. I wouldn't want to do hours of web browsing on it, but it's good for 10 minutes at a time. Likewise, I wouldn't want to try and pop my iPad out in a store to read a review of a product, but I would much prefer it for longer use. So to me it comes down to how you want to browse.
- The Evo's keyboard is great IMO for a phone. For me I can type around 40-50 WPM on the iPad, and about 30-40 WPM on the Evo using the stock keyboard. I just got Swype for the Evo, which I think will be faster once I get used to it. I wouldn't write a novel with it, but it's plenty good for responding to emails and such.
So, in a nutshell it comes down to how you want to use it. If you are looking for something that you will pop out and use a few minutes at a time throughout the day for web searches, news reading, some gaming/multimedia, and email (unless you need Exchange), go with the Evo. If you are looking for something with more fun/creative apps and something you'll sit down with and use for hours, go with the iPad.
Although they overlap quite a bit, they also complement each other very well since they are best suited for use at different times. Just don't go with both if you have a laptop--then it's too confusing on which device to use.