Spec
This is based on Santa Rosa platform (2007 Intel platform), so there is nothing much to say since the successor, current generation--Montevina platform-- is a bit better in almost every aspects. Anyway, the distinction here besides the screen is low-voltage CPU. It really helps boosting the battery life into over 5 hours easily while this is a bit high threshold for its generation and it's still performing good with 4MB L2 cache. You'll see later on.
Performance
Although the tablet PC doesn't need any kind of topnotch performance, a general idea how fast it is still concerned most people.
First with Windows Experience Index, as far as most people are concerned, this could easily compare to everyone's system without messing setting up anything else.
Start-up time: [from windows splash screen to be able to open ie8 with fully loaded myCapsules.com page. It's not necessarily complete loading everything though.]
wPrime -- testing multi-core CPU solely.
HDTune - for both internal SATA hard disk and the external one to see how good USB controller performs.
CrystalMark2004 -- it might be dated a bit, but you'll get a good idea.
PCMark05
3DMark06
Let's say that Warcraft III is able to play flawlessly, but I couldn't get all max--just some. I just hope I could play Diablo III as beautiful as the trailer was =) Otherwise I have to play on another machine which is sad!
Battery Life
This probably is the selling point of this machine. 8-cell battery with 66Wh can live up your machine 5 hour normally with Wifi on and <=30% screen brightness. In this scenario, it uses about 12.5-13.5W regularly. However, if you shut off all wirelesses, dim the screen all the way to the lowest, you might be able to reach 6 hours with 10-12W power consumption.
When playing 720p Xvid video, the processor usage is vary between 20%-60% and sucks the juice 20.2W maximum w/max brightness or about 17-18.8W when dimming you screen to my regular usage--40%). So you may get the idea on the shortest life this could be, 66/20 = 3 hours and 20 minutes.
In short, it's impressive, but not surprisingly fantastic this day.
Heat & Noise
It's almost impossible to hear the machine whining even though you would feel not that hot air coming out of air vent regularly. As a result, you will feel a bit warm on the palm rest, more specifically on the right side where WLAN card sit underneath. It also is very hot if you are using High Performance power plan, but almost no one wants to use that on the go anyway. Probably only when it sits at your desktop at work/home. I do recommend you to have a notebook cooler, it really helps.
In case you are using Power saver profile with maximum power saving for wireless setting, you will barely feel the heat from the machine, but that's a trade off for wireless range & performance as well. You have to try and see if that's possible for your scenario.
Service
This is the part I haven't had an experience much for most computers I bought. However, for X61T I had sent this to a repair center once, just to fix the BIOS error after updating via Vista. At first, it was great, IBM, repeatedly IBM is the one who is in charged for all Thinkpad machines, not Lenovo, sent me a box for shipping it to the repair center with overnight shipping free of charge if yours is under warranty. You could track all the process via IBM's web site instantly. Nonetheless, in my case--my very unlucky day perhaps, I got a wrong machine back after only couple days from the day I sent in. Although I made an arrangement to ship the wrong one back immediately. It took me full 36 day for waiting my tablet PC back home and more than >30 hours for >20 times calling about the issue. You can take a look for more detail here.
After my experience, I got 3-month warranty extra to cover their fault and an offer for memory or extend 6 more month of warranty from the Lenovo's employee. Sadly, it's just the offer, but no actual result or even any contact explaining what was happening really.
In brief, no matter how much I like Thinkpad machine, I couldn't stand to support their service, excuses, and liars. My best bet would be not to extend to any extra warranty, just find someone you trust to fix it and stay away from their depot or service center as much as you can. That's just me though; your mileage might be different story.
Drawback
Well, it's just normal for everything. Things always have good sides and of course bad sides. For Thinkpad X61T, it has a real pain issue of its own Multitouch feature. It's the driver for that which cannot work with Photoshop easily. In other words, without your effort, you will not be able to use pressure sensitivity in Photoshop. It's like Photoshop doesn't recognize the Wacom pen in a normal way. You will have to work around a bit to get it work. Some might find it's not working, some may find it work. This is the way to try so; if you have any difficulty getting it work, just ask.
One more thing I told you earlier is the microphone jack. It just doesn't work as it should be--I have to loose the microphone connector a bit to get it work. If you have X61T, please let me now if you have the same problem.
Next, I hate the thing that looks like it has, but actually doesn't. I'm talking about ThinkLight. If Lenove didn't want to have this feature, why on earth do they have it as Fn + PgUp. Although they might come up with an easy excuse like decreasing cost for creating a new layout, it still sucks not to get rid of it completely.
The last which I'm not sure I could count is its Ultrabase is soo expensive. Thus I couldn't buy it :-P
Conclusion
If you are looking for a professional tablet PC, Thinkpad X61 Tablet won't disappoint you since this is one of the most powerful tablet PC available. It's worth every penny although it's expensive. With all features like ActiveRotate, swivel screen, and Multitouch, can draw an attention from your friends easily, but those features will be useless without practicing. You just have to spend time to get used to, then you will be able to get the most of it.
For the time I'm writing, there are so many newer machines available but only some of them come with more powerful solution. You may have to decide between performance & battery life which is more important to you.
Pros:
Cons: