So I'll lay my full opinion on the table, as its a pretty recent experience for me. It's a long story, so if you're patient enough to read it, here it goes:
I pre-ordered an iPhone 4, and when I got it, it was defective. Not one of the reception issues or other things people were complaining about at the time... it was just defective. Being that stores hadn't even filled all of their pre-orders, there wasn't a chance in hell I was getting a replacement any time soon. I decided, since that had been my 3rd iPhone (had an original 2g, and a 3G-S before it) that I'd head to the Android side and try it out.
I don't remember how I found out about the Captivate, but I think a friend mentioned it and we started looking into it. It seemed like a great phone, but it wasn't being released until about 2 weeks down the line at this point in time. I spoke to some folks at Best Buy where I had bought the iPhone 4 and expressed my interest in the Captivate. I was able to get the Aria for the time being, and return it with no return fee and exchange it for the Captivate when it was released.
My first reactions with the Aria were mixed. I was blown away by Android from the start, but knowing (spec's wise) that the Captivate was a better phone I never took the time to fully appreciate it. I was also naive to many things about it since I was new to Android and hadn't fully wrapped my head around it yet. So, then I got my Captivate and dove head first into Android. At first I loved it. It's a powerful phone and does a lot of things real well. It has its downsides, though. My biggest gripe at first was the GPS. I use a GPS pretty frequently for various things, and I hadn't bought a new standalone GPS unit because I had this phone. So it not working mattered to me. It rarely connected at all until the over the air update. Then I randomly had problems with it turning itself off. My first one was fine for months, then one day I pulled it out of my pocket to check the time and it was off. Then it happened again the next day... and then twice the next. I got a warranty replacement. That one did the same thing after a month. Got that one replaced... lasted about 2 weeks, same problem. I charge the phone once a night when I get home from work until it's full, and unplug it afterwards. The battery usually lasts me to at least 40% even with heavy use on the average day... so can't see it being that I messed up all 3 batteries some how. Also, when I'd turn it back on the battery was never dead. I've never had a similar problem with any of the smartphones I've had in the past.
So, I went back to AT&T and told them I want an Aria instead. I had done some research on the Andriod phones available on AT&T currently and I thought it would be my next best option. I went on different forums, read reviews, went into stores and played with the different options, etc. I knew I would be making some concessions and giving up some things, but at this point I just wanted a reliable smartphone.
So I've had the Aria for a few days now (less than a week), but I already realize so many things that I hadn't noticed in comparison to the Captivate at first because I was new to Android and didn't know better. Here's my list:
1. I love Sense. I was ready to load up ADW right away because I was use to using it, because TouchWiz sucked. I can't see myself replacing Sense anytime soon.
2. The GPS works perfectly. Connects just about instantly, and is way more accurate than any of my Captivate's were.
3. I actually appreciate the small size more now after having a big 4" screen for a while. While it was weird to type on the smaller screen at first, SwiftKey made that all better. Now I don't want a big screen phone anymore.
4. Based off of the dBm and asu numbers, I actually get a little better reception on my Aria at the places I frequent most.
5. A lot of my favorite apps run generally less buggy on the Aria then on any of my Captivates. Handcent is one of them, for example.
6. Now, I don't know or care why, but stock vs. stock my Aria seems smoother, snappier, and faster navigating around general apps and such. No, games don't play better on it for obvious reasons. Everything else that I use, though... not laggy at all.
The bad:
1. Storage... not a lot of room for apps (though, I haven't run out yet). I stuck my 16gig stick in it for pictures and such, but without Froyo on it yet, the low internal storage thing kinda sucks. Yes I know I can put a froyo rom on it and store apps to SD. I may, but right now I don't have any need to.
2. The camera doesn't compare. The only thing it matches up to is megapixels, which mean nothing really. The Captivate camera, even without a flash, is amazing. The Aria camera still does the trick for simple stuff, though.
3. The optical wheel can be finicky, but maybe I'm just not use to it yet.
4. I wish the screen was a little bigger for certain websites and things... but its really not as bad as I'd thought it would be.
In all honestly... those 4 things are the worst I can say about it so far. It's a great phone, and its changed what I thought I "needed" in a smartphone.