[XPERIA X1 General] lazyjai:
Hmmm this is a hard one to tackle.... for me I always regret some part of the phone... maybe frustrated is the work I should use instead of regret. my phone progression has been

550 motorola flip --> Motorola TAC Elite --> Motorola QWERTY messaging phone (forgot the model) --> SE P800 --> BB 7250 & SE W900 --> BB 8830 & Nokia N95 --> BB 8830 & Nokia N85 -- BB 8830 & SE X1

the X1 marked a major change in the way I used my personal phone, primarily for e-mail and messaging, so my criteria have changed a bit. Although the N95/N85 were smart phones, i still primarily used them as phones, and not integrated messaging devices. The Blackberry was always for work, and has always primarily been a messaging device so I have drawn the baseline experience from that.

To answer your question in short: No. No serious regrets.

To answer you question in detail: Yes, I have regrets but the issues can be mitigated/X1 seemed to be the best blend of trade-offs:

1) Lack of free integrated international maps. Global data roaming costs and arm and a leg. Pay as you go in some countries don't include data, so Google Maps downloading data is a bit of a concern when i'm using the GPS abroad. This was a factor when I was deciding between the X1 or N97. I spend 9 of 12 months in home territory so i can probably manage without free international maps. (Garmin, Wayfinder don't have maps for Japan or other Asian countries that I spend time in, and you have to pay for maps unlike the free Nokia Maps app)

2) Windows Mobile quirkiness. WM 6.1 is slow. Weird things happen like accounts go missing, spontaneous reboots, lock ups, crashes, when you install different things. It's not as customizable (stock), I haven't found a voice dialler/voice synth, and the menu system is not intuitive. The messaging system is more robust however, and there is great aftermarket customization (ROMS and MODS from here), etc. I think some of these shortcommings can easily be rectified by the community, but they're still annoying. COmmunity and aftermarket support maturity ended up being a huge factor for me.

3) Form factor. It is slightly thicker than my N85, but thinner than my N95, just as wide, and only 1 cm or so taller. It is comfortable in my hand and is pocketable. The N97 is not much bigger, but the BB Bold is a lot fatter. Seemed like a good compromise.

4) Battery Life. Horrid. I could get 3-4 days normal use with my N85. I use 30% of the battery on a low usage day, and 50-60% on a moderate usage day. Mind you I use the data a lot more, which does suck up more battery, but I should get more than a day's charge out of it IMO. I'm going to chalk this up to my use of data, and hope that there is a future radio/rom upgrade that is easier on battery usage.

5) Functionality as a messaging device. I IM, e-mail, and SMS much more than I call. probably 8-to-1. I do find myself resorting back to my BB8830 for heavy IM usage sessions, possibly because I am more familiar with it, but realistically because I'm much more used to the keyboard. Heavily considered the BB Bold for this reason alone. Maybe things will change after a month or two getting used to the X1. The N97 which I also considered had serious issues as being a robust messaging device. It seemed adequate, and may have improved with further firmware releases/development, but S60 5th Edition seemed limited in more ways somehow.

6) Recessed screen. Pain in the ass. Not a deal breaker tho since I have thin fingers and am pretty dexterous. I can understand why this would be a larger issue for other people however. Definitely a poor design choice.

7) Volume. This is a quiet device. I'll have to amplify and re-jig all my custom call tones, and what not. Annoying, but manageable.

8) Poor camera. I'm used to a really good quality 5 MP Carl Zeiss lense that was on the N85. I didn't use it much but it was a nice thing to have as a backup. I feel a bit stifled by the camera on the X1, but since I'm not really using it that much, it becomes a lower weighted criteria.

So as you can see, for me, it was not a simple choice between a BB Bold, SE X1, Nokia N97, or waiting for the new Samsung B7610, HTC Touch 2, SE X2, or some other next gen device. Lots of factors, and yes I do have regrets around a lot of them, but you do the best you can and just move on.

I've found with some tweaking the X1 usable/tolerable, and meeting 80% of my needs. Nothing will ever be perfect, and if I follow the 80/20 rule, meeting 80% of my requirements for a decent price is usually as good a deal as I can ask for.