As a concept I like the iPhone immensely. For me, the original had too many shortfalls but the 2nd generation (3G) model is better. Although in reality there isn't much difference between them other then adding 3G and GPS. I very rarely make video calls, but I use my phone's 3G and GPS functionality quite a bit so their lack was a deal breaker for me.
There are other things I dislike but of course that applies to many consumer devices and one can work around or become attuned to them. Personally, for SMS I prefer traditional keys, I find them much faster and easier - especially for one handed operation.
The lack of out of the box MMS is an irritant and a bizzare oversight in Europe - although I seldom send MMS messages so it isn't quite a deal breaker. The inability to capture video is more of a nuisance, even more so is the lack of memory card facility. The release of Hyperoffice has negated some of my reservations about business connectivity.
What has primarily stopped me from buying one is Apple's continued protectionist attitudes - seeking to restrict 'who' can use one and on what network and/or tariff. The release on PAYG was a [small] step forward. Intial, short term network tie-ins are OK but it's been too long now and as all UK networks have long been fully capable of supporting all functionality, they should all be allowed to offer this product.
Apple's policy flies in the face of fair and open competition in the marketplace, but it's evidently in their nature, and IMO it has cost them dearly over the years. While I appreciate the rationale behind it, I think they have a tendency to carry it too far.
Speaking for myself, if I buy something, I consider it mine, to do with (e.g. personalise/customise) as I please. Nominal locking is acceptable, but IMO the lengths that some manufacturers (and not just Apple) go to to prevent it, is excessive.
I wish they would drop this elitist attitude, whatever device we're talking about - in the end it's only a phone/PC/audiovideo player ... but then I guess that's part of the appeal, for some at least.
I like the Blackberry too, but they are pitching their products at a different market segment, I'm not sure one can make a meaningful comparison beyond the technical and on that front I'd say the Apple has it.