Sorry but I had to jump on this.
I've also personally used both and (IMO) BerryWeather is better, hands down. The amount of user customization is ridiculous. But you have to have at least version 2.0 for most of the new features and they DO charge an upgrade fee when updating from version 1.x to 2.x. But I believe it's a discounted price. Check
Bellshare - Premium BlackBerry Apps for more info.
I say BerryWeather because of the features alone. First there is the Home Screen Wallpaper option - You choose your wallpaper and then adjust setting for how much info is displayed on your HS as well as where it shows on your HS. Next is the "cartoonish" icons - you are able to download new icon sets from within the app. Bellshare has setup and mobile site where most of the icon sets are stored and you can download as many different ones as you like and can easily switch them from within the app. Also, Themes In Motion has tons of icon sets for BerryWeather as well! Another feature is a notification icon - don't want to use the HS Wallpaper option and instead would prefer a tiny thermometer in your notifications? Easy, just gotta check that option within BerryWeather and it'll display the temp on most EVERY screen on your BB!
So there's a little taste of what BerryWeather has to offer! Personally, I recommend updating to the newer version, I did! Plus, there are more and more apps (and themes) that are offering BerryWeather (and BerryWeather ONLY) integration!
You can usually get BW at a discounted price because it get promoted so much!
And besides, read the reviews on anything and everything you are interested in! There is a reason BerryWeather has been voted (more than once) Best BlackBerry Weather Application...PERIOD! :D
Weather Plus IS a decent weather app and may be the application for you, I dunno, I'm not you. It may suit YOUR needs and at the end of the day, that's what's important! It's your BlackBerry, right?
I can relate with you on the not wanting to pay for the app twice because I went through the same thing at one point! But to be honest with you, the version of BW you're using now compared to the version you'd be upgrading to, well truthfully, there is no comparison. It'd truly be like buying a new application! You're missing out on many NEW & UPDATED features!
Posted from my CrackBerry at wapforums.crackberry.com