I am working with Wacom intuos 3 - excellent tool for Photoshop - It feels very natural to paint/retouch/draw with stylus, rather than mouse... (actually painting with mouse feels to me like trying to play piano with both hands in gypsum)
The size matters as some guys already mentioned - the biggest is not the best, as you will get tired moving your arm around all the surface on big ones... I do have A5 size and is enough for me (wouldn't go smaller) So A5-A4 size is good choice for photoshoping...
Personally I wouldn't go for the Cintiq version - costs are too high, and I don't believe the colors will be accurate on that TFT screen... (the Cintiqs are good for architects, illustrators and industrial designers...)
I've had my Intuous tablet for over a decade and it still works great. I've worked on the newer ones, and they're nice and all, but you can probably find an old one on Ebay and it'll do just fine. Mine has worked with a Mac G3, G4, G5, a Toshiba laptop, and now an iMac. Just don't get a tiny one! 8 or 9 inches is a good size.
I have the same tablet (intuos 4). I wish I only had more time to have fun with it and develop photoshop skills. Currently I mostly use it for manual selection (using Lasso tool in PS) when the auto selection (w-tool) fails and it's time demanding and not so comfortable to select with a mouse.
I've also tried hand drawing. It's quite fun. If I only had better artistic skills... :)
Yes I do! Can´t understand how I could live without it. On work I found myself automatically doing the hand moves I use when I use the tablet at home. Even if I dot have a tablet at work. :o) I find the tablet extremely useful even when I´m not using photoshop.
Touch screen monitors will be better, cause you will be drawing directly on the screen. On the other hand, you can't put your hand on the monitor, because it will feel whole your hand. A tablet is sensitive only for it's pen. I don't think it will be useful to use a touchscreen monitor.
With touchscreen monitors - the biggest drawback is color consistency. Working with photography on serious level requires precise colors (good monitor and calibration is a must)... The touchscreens are usually fitted with crappy TFT matrix (same as the cheapest monitors), so if you are color aware the red warning light in your head has just lit up... :) (This opinion might be obsolete, as technology moves on and maybe there are touchscreens with other matrixes already on the market)
Of-course, for illustrators and architects (and other areas where color is not vital) touchscreens are cool...