Heres my honest opinion and ill apologise if it comes across as fanboi-ish

. Ive had my BB Bold since last Dec and ill be honest no other device has and can come close to what it does..effective communication via email etc. I absolutely love the device and having owned Winmo and Symbian devices...the BB imho blows them all away.
Its pretty well built, but is a biggish device ie wide but its got some serious power...its got to the point that i no longer need to be sitting in front of my laptop or work pc to fire off an email...the keyboard on it is an absolute joy to use and makes life so much easier when emailing and texting.
Internet browsing isnt too bad really, theres no flash support sadly but skyfire the browser is currently in testing so should be available soon. Battery life is pretty good altho the more you use the device the more it drains but i get through a good days work before it gives up on me...ive always got it on charge when im at home and it uses a mini usb cable so you can charge from a laptop or pc.
What i would suggest you do is to pop into a tmobile store and ask if they have any demo units...if not they usually have a dummy unit which looks and weighs the same. You could if you wanted to pop into a Vodafone shop as they usually have demo units on display in most stores. Failing that just order one...you have 7 days in which to change your mind if you dont like it...probably the best way to see if you like it. You will have to pay an extra £10 on top for the Blackberry internet service and web n walk...without those the Bold doesnt really shine imho.
If you want to do some serious research on it then click the link underneath my sig

...thats the place to be for everything Blackberry including the Bold...in fact they have forums set out for each of the BB devices.
I'll say this though, with the Bold you will be very happy...id be suprised if you werent..they do the 8900 curve which lacks 3G but is smaller in the hand...its a very nice device...i had one from tmobile as thats who im with...sent it back as couldnt live without 3G...in fact end of april was my upgrade so i got another Bold from tmobile...this one is network branded whereas my original Bold isnt...sim free. Ive just unlocked the one i got from tmobile and have put it up for sale to see if i get any interest in it....if not ill be running it as a backup device.
Now getting onto the G1...if you really want an Android phone then i suggest you go to Vodafone and get the HTC Magic...i picked one up last week and i have to say its thoroughly impressed me..its much nicer and better looking than that fugly G1...that phone looks like a toy

. But im having immense fun with the Magic...i got it on a £35 per month tariff with 600 mins, unlimited texts and unlimited internet....mind you im using it as a media device..downloaded a fair few apps and games on it.
So there you go mate...seriously id do some research on a BB before getting one...if you still want one then go for it but you may find it isnt quite the device for you especially if your not into emailing and staying in touch whilst on the move...thats why i suggest heading over to
www.crackberry.com and read about the phones and peoples general opinions on it..most of them are Canadian/American but im on there most of the times. Take some of the stuff there with a pinch of salt as some people just like ot moan for the sake of it.
Good luck with your decision though.